#include <iostream>
//using namespace std;
typedef unsigned long long ul;
typedef signed long long ll;

int main(void)
{
  std::cin.tie(0);
  std::ios::sync_with_stdio(false);
  std::cout << std::fixed;
  ll a, b, c, d;
  std::cin >> a >> b >> c >> d;
  std::cout << (a*b*c)%d << std::endl;
  return 0;
}