#define _CRT_SECURE_NO_WARNINGS  
#include <stdio.h>
#include <iostream>
#include <algorithm>
#include<string>
#include <math.h>
#include<vector>
#include <math.h>

using namespace std;


int main() {
	long long a, b, c, d;
	cin >> a >> b >> c >> d;
	long long ans;
	ans = a * b; 
	ans = ans*c;
	ans = ans%d;
	cout << ans << endl;
	return 0;
}