#include <bits/stdc++.h>

using namespace std;

#define LL long long

int main() {
    LL a, b, c, d;
    cin >> a >> b >> c >> d;
    LL ans = a % d;
    ans = (ans * (b % d)) % d;
    ans = (ans * (c % d)) % d;
    cout << ans << endl;
    return 0;
}