#include <stdio.h>
int main(){
  long long int a,b,c,d;
  long long int ans;
  scanf("%lld %lld %lld %lld",&a,&b,&c,&d);
  ans=a%d;
  ans=(ans*b)%d;
  ans=(ans*c)%d;
  printf("%lld\n",ans);
  return 0;
}