#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
#define FOR(i,a,b) for(int i = (a); i < (b); ++i)
#define REP(i,n) FOR(i,0,n)
#define SZ(n) (int)(n).size()
#define ALL(n) (n).begin(), (n).end()
#define MOD 1000000007
using namespace std;
typedef long long LL;
typedef vector<int> VI;

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