#include <bits/stdc++.h>
using namespace std;
 
typedef long long ll;
typedef pair<int,int> P;
 
const int INF = 1e9;
const int mod = 1e9+7;
const double EPS = 1e-10;
const double PI = acos(-1.0);
 
int main()
{
    ll a,b,c,d,res = 0;
    cin >> a >> b >> c >> d;
    res = a * b % d;
    res = res * c % d;
    cout << res << endl;

    return 0;
}