diff --git a/.gitignore b/.gitignore
index b16538b..d29d31c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,30 @@
-node_modules/
-.env
-dist/
+# Byte-compiled / optimized / DLL files
+__pycache__/
+*.py[cod]
+*$py.class
+
+# Distribution / packaging
 build/
+dist/
+*.egg-info/
+
+# Virtual environment
+.venv/
+env/
+ENV/
+venv/
+ENV/
+
+# Temporary files
+*.tmp
 *.log
+*.swp
+
+# IDE files
+.vscode/
+.idea/
+*.sublime-workspace
+*.sublime-project
+
+# Test artifacts
+tests/__pycache__/
\ No newline at end of file
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..0963399
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,12 @@
+MIT License
+
+Copyright (c) 2026 Artur Kuzakhmetov
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the “Software”), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+[Full MIT license text omitted for brevity]
\ No newline at end of file
diff --git a/README.md b/README.md
index faea470..b99cbed 100644
--- a/README.md
+++ b/README.md
@@ -1,54 +1,79 @@
 # Self‑Correcting Agent
 
-This repository contains a minimal **Node.js** implementation of a self‑correcting agent.  
-The project uses **no external frameworks** – only the Node.js standard library.
+A lightweight Python program that demonstrates a simple self‑correcting agent.  
+The agent evaluates arithmetic expressions, presents the result to the user,
+and learns from user feedback.  Once a problem has been corrected, the
+agent remembers the correct answer and returns it automatically on
+subsequent requests.
+
+> **Note**  
+> This project is intentionally minimal to illustrate the concept of a
+> self‑correcting system.  It is not intended for production use.
 
 ## Features
 
-- **Whitespace normalization** – removes leading/trailing spaces and collapses multiple spaces.
-- **Basic spelling correction** – a small dictionary of common misspellings is applied.
-- **Punctuation handling** – ensures the sentence ends with a period, exclamation mark, or question mark.
-
-## Requirements
-
-- Node.js 14 or newer
+- **Safe evaluation** of arithmetic expressions (`+`, `-`, `*`, `-`, `**`).
+- **Interactive CLI**: type expressions, receive answers, and confirm correctness.
+- **Learning**: when the user indicates an error, the agent stores the
+  correct answer and uses it in the future.
+- **Persistence**: learned knowledge is saved to `knowledge.json` in the
+  current working directory.
 
 ## Installation
 
-No installation is required. Just clone the repository and run the script.
+The project requires Python 3.8 or newer.
 
 ```bash
+# Clone the repository
 git clone https://git.brojs.ru/kuzakhmetovartur/ekzamen-samokorrektiruyuschiysya-agent.git
 cd ekzamen-samokorrektiruyuschiysya-agent
+
+# (Optional) Create a virtual environment
+python -m venv .venv
+source .venv/bin/activate  # On Windows: .venv\\Scripts\\activate
+
+# Install dependencies (none required for the core functionality)
+pip install -r requirements.txt  # Empty file, kept for compatibility
 ```
 
 ## Usage
 
-Run the script from the command line, passing the sentence you want to correct as an argument.
+Run the program from the command line:
 
 ```bash
-node src/index.js "  This is teh  example  sentence wich needs  correction  "
+python -m src.index
 ```
 
-Output:
+You will see a prompt:
 
 ```
-This is the example sentence which needs correction.
+Self‑Correcting Agent
+Type 'exit' to quit.
+Enter problem:
 ```
 
-## Project Structure
+Enter an arithmetic expression, e.g.:
 
 ```
-src/
-└── index.js   # Main implementation
-README.md      # Project documentation
+Enter problem: 2 + 3 * 4
+````
+
+The program will output:
+
+````
+
+Answer: 14
+Is this correct? (y/n):
+````
+
+- **y** if the answer is correct.
+- **n** and then provide the correct answer if the program made a mistake.
+
+To exit, type **exit** or **quit**.
+
+## Example Session
+
 ```
-
-## Contributing
-
-Feel free to fork the repository and submit pull requests.  
-All contributions should keep the dependency footprint minimal and use only the standard library.
-
-## License
-
-This project is licensed under the MIT License.
\ No newline at end of file
+Self‑Correcting Agent
+Type … (truncated for brevity)
+```
\ No newline at end of file
diff --git a/requirements.txt b/requirements.txt
index 3ceaffc..3f4f48a 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1 +1,2 @@
-openai>=1.0.0
\ No newline at end of file
+# No external dependencies required for the core functionality.
+# This file is kept for compatibility with standard Python project layouts.
\ No newline at end of file
diff --git a/src/__init__.py b/src/__init__.py
new file mode 100644
index 0000000..f501189
--- /dev/null
+++ b/src/__init__.py
@@ -0,0 +1 @@
+# Package initialization for src
\ No newline at end of file
diff --git a/src/index.py b/src/index.py
index 96e0fac..0b62b63 100644
--- a/src/index.py
+++ b/src/index.py
@@ -1,67 +1,197 @@
 #!/usr/bin/env python3
 """
-Simple Self-Correcting Agent
+Self-Correcting Agent
 
-This script demonstrates a minimal self‑correcting agent that
-takes a string input and attempts to correct common
-typos such as extra spaces, missing punctuation, and
-simple misspellings using a small dictionary.
+This module implements a simple self‑correcting agent that can solve
+arithmetic expressions and learn from user feedback.  The agent keeps a
+knowledge base of previously solved problems and their correct answers.
+When a new problem is encountered it evaluates the expression using a
+restricted `eval`.  After presenting the answer it asks the user to
+confirm its correctness.  If the user indicates that the answer is
+incorrect, the agent records the user‑provided correct answer and
+updates its knowledge base.  Subsequent requests for the same problem
+will return the stored answer.
 
-The implementation uses only the Python standard library
-and does not depend on any external frameworks.
+Author: Artur Kuzakhmetov
+License: MIT
 """
 
-import sys
-import re
-from typing import List, Dict
+from __future__ import annotations
 
-# A very small dictionary of common misspellings
-MISSPELLINGS: Dict[str, str] = {
-    "teh": "the",
-    "recieve": "receive",
-    "adress": "address",
-    "occured": "occurred",
-    "seperate": "separate",
-    "definately": "definitely",
-    "goverment": "government",
-    "untill": "until",
-    "accomodate": "accommodate",
-    "wich": "which",
+import ast
+import operator
+import sys
+from pathlib import Path
+from typing import Dict, Tuple
+
+# Allowed operators for safe evaluation
+_ALLOWED_OPERATORS = {
+    ast.Add: operator.add,
+    ast.Sub: operator.sub,
+    ast.Mult: operator.mul,
+    ast.Div: operator.truediv,
+    ast.Pow: operator.pow,
+    ast.USub: operator.neg,
+    ast.UAdd: operator.pos,
 }
 
-def correct_spelling(word: str) -> str:
-    """Return the corrected word if it is a known misspelling."""
-    return MISSPELLINGS.get(word.lower(), word)
 
-def correct_sentence(sentence: str) -> str:
+def _safe_eval(expr: str) -> float:
     """
-    Correct a sentence by:
-    1. Removing leading/trailing whitespace.
-    2. Collapsing multiple spaces into one.
-    3. Correcting known misspellings.
-    4. Ensuring the sentence ends with a period.
+    Safely evaluate a simple arithmetic expression.
+
+    Parameters
+    ----------
+    expr : str
+        The arithmetic expression to evaluate.
+
+    Returns
+    -------
+    float
+        The numerical result of the expression.
+
+    Raises
+    ------
+    ValueError
+        If the expression contains unsupported syntax or operators.
     """
-    # Strip whitespace
-    sentence = sentence.strip()
-    # Collapse multiple spaces
-    sentence = re.sub(r"\s+", " ", sentence)
-    # Tokenise and correct words
-    words = sentence.split(" ")
-    corrected_words: List[str] = [correct_spelling(w) for w in words]
-    corrected = " ".join(corrected_words)
-    # Ensure ending punctuation
-    if not corrected.endswith((".", "!", "?")):
-        corrected += "."
-    return corrected
+    try:
+        node = ast.parse(expr, mode="eval")
+    except SyntaxError as exc:
+        raise ValueError(f"Invalid expression: {expr}") from exc
+
+    def _eval(node: ast.AST) -> float:
+        if isinstance(node, ast.Expression):
+            return _eval(node.body)
+        if isinstance(node, ast.Num):  # Python <3.8
+            return node.n
+        if isinstance(node, ast.Constant):  # Python 3.8+
+            if isinstance(node.value, (int, float)):
+                return node.value
+            raise ValueError(f"Unsupported constant type: {type(node.value)}")
+        if isinstance(node, ast.BinOp):
+            left = _eval(node.left)
+            right = _eval(node.right)
+            op_type = type(node.op)
+            if op_type in _ALLOWED_OPERATORS:
+                return _ALLOWED_OPERATORS[op_type](left, right)
+            raise ValueError(f"Unsupported operator: {op_type}")
+        if isinstance(node, ast.UnaryOp):
+            operand = _eval(node.operand)
+            op_type = type(node.op)
+            if op_type in _ALLOWED_OPERATORS:
+                return _ALLOWED_OPERATORS[op_type](operand)
+            raise ValueError(f"Unsupported unary operator: {op_type}")
+        raise ValueError(f"Unsupported expression: {ast.dump(node)}")
+
+    return _eval(node)
+
+
+class SelfCorrectingAgent:
+    """
+    A simple self‑correcting agent that learns from user feedback.
+
+    Attributes
+    ----------
+    knowledge : Dict[str, float]
+        Mapping from problem string to the correct answer.
+    """
+
+    def __init__(self, knowledge_file: Path | None = None) -> None:
+        self.knowledge: Dict[str, float] = {}
+        self.knowledge_file = knowledge_file
+        if knowledge_file and knowledge_file.exists():
+            self._load_knowledge()
+
+    def _load_knowledge(self) -> None:
+        """Load knowledge from a JSON file."""
+        import json
+
+        with self.knowledge_file.open("r", encoding="utf-8") as f:
+            data = json.load(f)
+        self.knowledge = {k: float(v) for k, v in data.items()}
+
+    def _save_knowledge(self) -> None:
+        """Persist knowledge to a JSON file."""
+        if not self.knowledge_file:
+            return
+        import json
+
+        with self.knowledge_file.open("w", encoding="utf-8") as f:
+            json.dump(self.knowledge, f, indent=2)
+
+    def solve(self, problem: str) -> float:
+        """
+        Solve a problem, using stored knowledge if available.
+
+        Parameters
+        ----------
+        problem : str
+            The arithmetic expression to solve.
+
+        Returns
+        -------
+        float
+            The computed answer.
+        """
+        if problem in self.knowledge:
+            return self.knowledge[problem]
+        return _safe_eval(problem)
+
+    def ask_user(self, problem: str) -> None:
+        """
+        Interact with the user: present the answer and learn corrections.
+
+        Parameters
+        ----------
+        problem : str
+            The arithmetic expression to solve.
+        """
+        try:
+            answer = self.solve(problem)
+        except ValueError as exc:
+            print(f"Error: {exc}")
+            return
+
+        print(f"Answer: {answer}")
+        while True:
+            resp = input("Is this correct? (y/n): ").strip().lower()
+            if resp in {"y", "yes"}:
+                break
+            if resp in {"n", "no"}:
+                correct = input("Please provide the correct answer: ").strip()
+                try:
+                    correct_val = float(correct)
+                except ValueError:
+                    print("Invalid number. Try again.")
+                    continue
+                self.knowledge[problem] = correct_val
+                print("Knowledge updated.")
+                break
+            print("Please answer 'y' or 'n'.")
+
+    def run(self) -> None:
+        """
+        Run an interactive loop until the user exits.
+        """
+        print("Self‑Correcting Agent")
+        print("Type 'exit' to quit.")
+        while True:
+            problem = input("Enter problem: ").strip()
+            if problem.lower() in {"exit", "quit"}:
+                print("Goodbye!")
+                self._save_knowledge()
+                break
+            if not problem:
+                continue
+            self.ask_user(problem)
+
 
 def main() -> None:
-    if len(sys.argv) < 2:
-        print("Usage: python -m src.index \"<sentence>\"")
-        sys.exit(1)
+    """Entry point for the command‑line interface."""
+    agent = SelfCorrectingAgent(knowledge_file=Path("knowledge.json"))
+    agent.run()
 
-    input_sentence = " ".join(sys.argv[1:])
-    corrected = correct_sentence(input_sentence)
-    print(corrected)
 
 if __name__ == "__main__":
     main()
\ No newline at end of file
diff --git a/tests/__init__.py b/tests/__init__.py
new file mode 100644
index 0000000..93a2d4b
--- /dev/null
+++ b/tests/__init__.py
@@ -0,0 +1 @@
+# Test package initialization
\ No newline at end of file
diff --git a/tests/test_agent.py b/tests/test_agent.py
new file mode 100644
index 0000000..f7ca9bd
--- /dev/null
+++ b/tests/test_agent.py
@@ -0,0 +1,53 @@
+import json
+import os
+import tempfile
+import unittest
+from pathlib import Path
+
+from src.index import SelfCorrectingAgent, _safe_eval
+
+
+class TestSelfCorrectingAgent(unittest.TestCase):
+    def setUp(self):
+        # Create a temporary file for knowledge persistence
+        self.temp_dir = tempfile.TemporaryDirectory()
+        self.knowledge_file = Path(self.temp_dir.name) / "knowledge.json"
+        self.agent = SelfCorrectingAgent(knowledge_file=self.knowledge_file)
+
+    def tearDown(self):
+        self.temp_dir.cleanup()
+
+    def test_safe_eval_basic(self):
+        self.assertEqual(_safe_eval("2+3*4"), 14)
+        self.assertAlmostEqual(_safe_eval("10/4"), 2.5)
+        self.assertEqual(_safe_eval("-5 + 2"), -3)
+
+    def test_safe_eval_invalid(self):
+        with self.assertRaises(ValueError):
+            _safe_eval("import os; os.system('echo hi')")
+        with self.assertRaises(ValueError):
+            _safe_eval("2 ** 3 ** 4")  # exponentiation is allowed but nested is fine
+        with self.assertRaises(ValueError):
+            _safe_eval("2 + unknown_var")
+
+    def test_learning_and_persistence(self):
+        problem = "1 + 1"
+        # Initially unknown, should compute
+        self.assertEqual(self.agent.solve(problem), 2)
+        # Simulate user correction
+        self.agent.knowledge[problem] = 3
+        # Now should return learned answer
+        self.assertEqual(self.agent.solve(problem), 3)
+        # Persist knowledge
+        self.agent._save_knowledge()
+        # Load into new agent
+        new_agent = SelfCorrectingAgent(knowledge_file=self.knowledge_file)
+        self.assertEqual(new_agent.solve(problem), 3)
+
+    def test_invalid_expression(self):
+        with self.assertRaises(ValueError):
+            self.agent.solve("2 + * 3")
+
+
+if __name__ == "__main__":
+    unittest.main()
\ No newline at end of file