def factorial(n):
    """
    Calculate the factorial of a non-negative integer n.
 
    Parameters:
    n (int): A non-negative integer whose factorial is to be calculated
 
    Returns:
    int: Factorial of the given number n
    """
    if n < 0:
        raise ValueError("Factorial is not defined for negative numbers")
    elif n == 0 or n == 1:
        return 1
    else:
        return n * factorial(n - 1)
 
# Example usage:
# print(factorial(5))  # Output: 120

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