#include<iostream>
#include<string>
#include<vector>
#include<map>

using namespace std;

unsigned long long a, b,c,d;

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