#define _USE_MATH_DEFINES
#include<stdio.h>
#include<string>
#include<iostream>
#include<cctype>
#include<cstdio>
#include<vector>
#include<stack>
#include<queue>
#include <algorithm>
#include<math.h>
#include<set>
#include<map>
#include<iomanip>

//#include<bits/stdc++.h>



using namespace std;


bool F[10008];

int main() {

	unsigned long long int a,b,c,d;
	cin>>a>>b>>c>>d;
	a*=b;
	a%=d;
	a*=c;
	a%=d;
	cout<<a<<endl;
	return 0;
}