#include <iostream>
using namespace std;

int main(){
  long long unsigned a,b,c,d;
  long long unsigned ans;

  cin >> a>> b >> c >> d;
  a%=d;
  b%=d;
  c%=d;
  ans=(((a*b)%d)*c)%d;

  cout << ans<<endl;

  
  return 0;
}