#!/usr/bin/env python3

"""Calcul de l'opposé d'un ensemble"""

import sys


def main():
    if len(sys.argv) == 3:
        a = int(sys.argv[1])
        n = int(sys.argv[2])
    else:
        a = int(input("a : "))
        n = int(input("n : "))

    oppose = opposer(a, n)
    print(f"L'opposé de {a} dans Z/{n}Z est {oppose}")


def opposer(a: int, n: int) -> int:
    return (n - a) % n


if __name__ == "__main__":
    main()