#include <stdio.h>
#include <algorithm>
#include <vector>
#include <deque>
#include <string>
#include <iostream>
using namespace std;
using ll = long long;

void solve();
int main() {
	solve();
#ifdef DBG
	while (true);
#endif
}


//373
void solve() {
	ll A, B, C, D, r;
	scanf("%lld %lld %lld %lld", &A, &B, &C, &D);
	A %= D, B %= D, C %= D;
	r = A * B % D;
	r = r * C % D;
	printf("%lld\n", r);
}