#include<iostream>
#include<string>
#include<cstdio>
using namespace std;

int main(){
    unsigned long long int A,B,C,D;
    cin >> A >> B >> C >> D;
    A = A%D;
    B = B%D;
    A = (A*B)%D;
    C = C%D;
    cout << (A*C)%D;
    return 0;
}