#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <queue>
#include <stack>
#include <complex>

using namespace std;

using ull = unsigned long long;
using ll = long long;
using ld = long double;

int main(){

	ll a, b, c, d;
	cin >> a >> b >> c >> d;
	cout << ((a * b) * c) % d << endl;

}