# -*- coding: utf-8 -*-
"""
No.373 かけ算と割った余り
https://yukicoder.me/problems/no/373

"""
import sys
from sys import stdin
input = stdin.readline


def main(args):
    A, B, C, D = map(int, input().split())
    ans = (A * B * C) % D
    print(ans)


if __name__ == '__main__':
    main(sys.argv[1:])