Write a Python function add_numbers(a, b) that takes two integers as input and returns their sum.

Example:

add_numbers(3, 5)  # Output: 3+5 = 8
add_numbers(10, -2)  # Output: 10+ (-2) = 8
add_numbers(5, -5)  # Output: 5 + (-5) = 0

Constraints:

• The inputs will always be integers.
• The function should handle both positive and negative integers.