#include<iostream>
#include<string>
#include<algorithm>
#include<cctype>
#include<set>
#include<bitset>
#include<math.h>
#include<map>
#include<queue>
#include<iomanip>
using namespace std;
#ifdef _WIN32
#include <Windows.h>
#endif

int main()
{
    long long a, b, c, d;
    cin >> a >> b >> c >> d;
    long long a1 = a%d, b1 = b%d, c1 = c%d;
    cout << ((a1*b1)%d*c1)%d << endl;
}