diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..ad4a1f1
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,176 @@
+# Created by https://www.toptal.com/developers/gitignore/api/python
+# Edit at https://www.toptal.com/developers/gitignore?templates=python
+
+### Python ###
+# Byte-compiled / optimized / DLL files
+__pycache__/
+*.py[cod]
+*$py.class
+
+# C extensions
+*.so
+
+# Distribution / packaging
+.Python
+build/
+develop-eggs/
+dist/
+downloads/
+eggs/
+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+wheels/
+share/python-wheels/
+*.egg-info/
+.installed.cfg
+*.egg
+MANIFEST
+
+# PyInstaller
+#  Usually these files are written by a python script from a template
+#  before PyInstaller builds the exe, so as to inject date/other infos into it.
+*.manifest
+*.spec
+
+# Installer logs
+pip-log.txt
+pip-delete-this-directory.txt
+
+# Unit test / coverage reports
+htmlcov/
+.tox/
+.nox/
+.coverage
+.coverage.*
+.cache
+nosetests.xml
+coverage.xml
+*.cover
+*.py,cover
+.hypothesis/
+.pytest_cache/
+cover/
+
+# Translations
+*.mo
+*.pot
+
+# Django stuff:
+*.log
+local_settings.py
+db.sqlite3
+db.sqlite3-journal
+
+# Flask stuff:
+instance/
+.webassets-cache
+
+# Scrapy stuff:
+.scrapy
+
+# Sphinx documentation
+docs/_build/
+
+# PyBuilder
+.pybuilder/
+target/
+
+# Jupyter Notebook
+.ipynb_checkpoints
+
+# IPython
+profile_default/
+ipython_config.py
+
+# pyenv
+#   For a library or package, you might want to ignore these files since the code is
+#   intended to run in multiple environments; otherwise, check them in:
+# .python-version
+
+# pipenv
+#   According to pypa/pipenv#598, it is recommended to include Pipfile.lock in version control.
+#   However, in case of collaboration, if having platform-specific dependencies or dependencies
+#   having no cross-platform support, pipenv may install dependencies that don't work, or not
+#   install all needed dependencies.
+#Pipfile.lock
+
+# poetry
+#   Similar to Pipfile.lock, it is generally recommended to include poetry.lock in version control.
+#   This is especially recommended for binary packages to ensure reproducibility, and is more
+#   commonly ignored for libraries.
+#   https://python-poetry.org/docs/basic-usage/#commit-your-poetrylock-file-to-version-control
+#poetry.lock
+
+# pdm
+#   Similar to Pipfile.lock, it is generally recommended to include pdm.lock in version control.
+#pdm.lock
+#   pdm stores project-wide configurations in .pdm.toml, but it is recommended to not include it
+#   in version control.
+#   https://pdm.fming.dev/#use-with-ide
+.pdm.toml
+
+# PEP 582; used by e.g. github.com/David-OConnor/pyflow and github.com/pdm-project/pdm
+__pypackages__/
+
+# Celery stuff
+celerybeat-schedule
+celerybeat.pid
+
+# SageMath parsed files
+*.sage.py
+
+# Environments
+.env
+.venv
+env/
+venv/
+ENV/
+env.bak/
+venv.bak/
+
+# Spyder project settings
+.spyderproject
+.spyproject
+
+# Rope project settings
+.ropeproject
+
+# mkdocs documentation
+/site
+
+# mypy
+.mypy_cache/
+.dmypy.json
+dmypy.json
+
+# Pyre type checker
+.pyre/
+
+# pytype static type analyzer
+.pytype/
+
+# Cython debug symbols
+cython_debug/
+
+# PyCharm
+#  JetBrains specific template is maintained in a separate JetBrains.gitignore that can
+#  be found at https://github.com/github/gitignore/blob/main/Global/JetBrains.gitignore
+#  and can be added to the global gitignore or merged into this file.  For a more nuclear
+#  option (not recommended) you can uncomment the following to ignore the entire idea folder.
+#.idea/
+
+### Python Patch ###
+# Poetry local configuration file - https://python-poetry.org/docs/configuration/#local-configuration
+poetry.toml
+
+# ruff
+.ruff_cache/
+
+# LSP config files
+pyrightconfig.json
+
+# End of https://www.toptal.com/developers/gitignore/api/python
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..b906acc
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2025 Pavel Kuliaka
+
+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:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/src/fast_pow.py b/src/fast_pow.py
index 1ba1dc1..52321e6 100644
--- a/src/fast_pow.py
+++ b/src/fast_pow.py
@@ -1,6 +1,18 @@
-def fastPow(number, power):
-    result = number
-    while power != 1:
-        result *= result
-        power = power // 2
+def fast_pow(number: int, power: int) -> int:
+    if not isinstance(number, int) or not isinstance(power, int):
+        raise TypeError("Arguments must be of integer type")
+    if power < 0:
+        raise ValueError("The power must be a positive number")
+    
+    if power == 0:
+        return 1
+    
+    result = 1
+    base = number
+    while power > 0:
+        if power % 2 == 1:
+            result *= base
+        base *= base
+        power //= 2
+
     return result
diff --git a/src/luhn.py b/src/luhn.py
index 11d993c..caf2de2 100644
--- a/src/luhn.py
+++ b/src/luhn.py
@@ -1,14 +1,44 @@
-def luhnСheck(cardNumber):
-    digits = [int(d) for d in str(cardNumber) if d.isdigit()]
+def luhn_check(card_number: str) -> bool:
+    if not isinstance(card_number, str):
+        raise TypeError("Card number value must be of string type")
+    if not all([symbol in '0123456789 ' for symbol in card_number]):
+        raise ValueError("The argument must be a string of numbers separated by spaces or without them")
+    
+    digits = [int(d) for d in str(card_number) if d.isdigit()]
+
+    if len(digits) < 2:
+        raise ValueError("The argument must be a string of numbers (more than 1) separated by spaces or without them")
+
     control = digits.pop()
-    parity = (len(digits))%2
+    digits_reversed = digits[::-1]
     total = 0
-    for i in range(len(digits)):
-        if i % 2 == parity:
-            doubled = digits[i] * 2
+    for i in range(len(digits_reversed)):
+        if i % 2 == 0:
+            doubled = digits_reversed[i] * 2
             if doubled > 9:
                 doubled -= 9
             total += doubled
         else:
-            total += digits[i]
+            total += digits_reversed[i]
+    
     return (total + control) % 10 == 0
+
+
+def util() -> None:
+    while True:
+        try:
+            user_input = input("Enter the card number: \n")
+            if user_input == "-1":
+                return
+            result = luhn_check(user_input)
+            if result:
+                print("Correct!")
+            else:
+                print("Incorrect")
+        except ValueError:
+            print("The card number must be a string of numbers (more than 1) separated by spaces or without them")
+        except KeyboardInterrupt:
+            print("To exit, please enter -1")
+
+
+util()
diff --git a/test/test_fast_pow.py b/test/test_fast_pow.py
index 5e4aebd..ca15e50 100644
--- a/test/test_fast_pow.py
+++ b/test/test_fast_pow.py
@@ -1,9 +1,23 @@
-from src.fast_pow import fastPow
+from src.fast_pow import fast_pow
 
 
 def test_two_power_two():
-    assert fastPow(2, 2) == 4
+    assert fast_pow(2, 2) == 4
 
 
 def test_negative():
-    assert fastPow(-1, 4) == 1
+    assert fast_pow(-1, 4) == 1
+
+
+def test_zero():
+    assert fast_pow(4, 0) == 1
+
+
+def test_incorrect_number():
+    fast_pow("124", 4)
+    assert False
+
+
+def test_incorrect_power():
+    fast_pow(124, "4")
+    assert False
diff --git a/test/test_luhn.py b/test/test_luhn.py
index 1c021a2..c0144f1 100644
--- a/test/test_luhn.py
+++ b/test/test_luhn.py
@@ -1,9 +1,24 @@
-from src.luhn import luhnСheck
+from src.luhn import luhn_check
 
 
 def test_good():
-    assert luhnСheck("8571 2612 1234 5467")
+    assert luhn_check("4532 0151 1283 0366")
 
 
 def test_bad():
-    assert not luhnСheck("4561 2612 1234 5463")
\ No newline at end of file
+    assert not luhn_check("4561 2612 1234 5463")
+
+
+def test_incorrect_data():
+    luhn_check("adghjdfg asdggf ad ff 1")
+    assert False
+
+
+def test_not_enough_numbers():
+    luhn_check("1")
+    assert False
+
+
+def test_empty_value():
+    luhn_check("")
+    assert False