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

using namespace std;

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


int main(){

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

}