#include <bits/stdc++.h>

using namespace std;

int main() {
    long long a, b, c, d;
    cin >> a >> b >> c >> d;
    a %= d;
    b %= d;
    c %= d;

    a = (a * b) % d;
    a = (a * c) % d;
    cout << a << endl;
    return 0;
}