#include<iostream>
#include<string>
#include<algorithm>
#include<cmath>
#include<iomanip>
#include<cstring>
#include<map>
#include<vector>
#include<queue>
#include<climits>
using namespace std;
typedef long long int ll;

int main(){

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