#include<iostream>
#include<string>
#include<algorithm>
#include<functional>
#include<vector>
#include<set>
#include<queue>
#include<list>
#include<stdio.h>
#include<stdlib.h>
#include<map>
#include<cstdio>

#define rep(i,a,b) for(int i=a;i<b;i++)
#define rrep(i,a,b) for(int i=a;i>=b;i--)
#define fore(i,a) for(auto &i:a)
#define all(x) (x).begin(),(x).end()

typedef long long ll;



using namespace std;

signed main() {
	ll a, b, c, d;
	cin >> a >> b >> c >> d;
	ll s = a*b%d*c%d;
	cout << s << endl;
	return 0;
}