#include <stdio.h>

int main(void)
{
  long int a,b,c,d;
  long int ans;
  long int ans2;
  
  scanf("%ld",&a);
  scanf("%ld",&b);
  scanf("%ld",&c);
  scanf("%ld",&d);

  ans = (a*b)%d;
  ans2 = ans*c;

  ans2 =ans2%d;
  printf("%ld", ans2);

  return 0;
}