#include <bits/stdc++.h>
#define rep(i, a, n) for(int i = a; i < n; i++)
#define repb(i, a, b) for(int i = a; i >= b; i--)
#define all(a) a.begin(), a.end()
#define int long long
using namespace std;


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