#include <iostream>
#include <cmath>
#include <string>
#include <vector>
#include <map>
#include <set>
#include <list>
#include <deque>
#include <algorithm>
#include <iomanip>
#include <functional>

#define REP(i, n) for(int i = 0;i < (n); i++)
#define REP2(i, x, n) for(int i = (x); i < (n); i++)
#define REPR(i, n) for(int i = (n); i >= 0; i--)

#define ALL(a) (a).begin(),(a).end()
#define SORT(c) sort((c).begin(),(c).end())

#define LL long long int
#define LD long double

#define PI 3.14159265358979

using namespace std;
//============================================
// 二分探索
int binary_search(vector<int>ary, int key, int imin, int imax) {
	if (imax < imin) {
		return -1;
	} else {
		int imid = imin + (imax - imin) / 2;
		if (ary[imid] > key) {
			return binary_search(ary, key, imin, imid - 1);
		} else if (ary[imid] < key) {
			return binary_search(ary, key, imid + 1, imax);
		} else {
			return imid;
		}
	}
}

//================================================
int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);

	LL A, B, C, D;
	cin >> A >> B >> C >> D;

	cout << A % D * B % D * C % D << "\n";
	return 0;
}