#! /usr/bin/env python3

def summe(a: int, b: int, c=0, d=None) -> int:
    result = a + b + c

    if d is not None:
        result += d

    return result


print("1. Summe:", summe(1, 2))
print("2. Summe:", summe(1, 2, 3, 4))
