#include <bits/stdc++.h>
using namespace std;

using ull = unsigned long long;
using ll = long long;

int main()
{
    ll a,b,c,d;
    cin >> a >> b >> c >> d;

    ll tmp1 = (a*b)%d;
    ll tmp2 = (tmp1*c)%d;

    cout << tmp2 %d << endl;
}