import java.util.*;

public class Exercise61{
  public static void main (String[] args){

    Scanner sc = new Scanner(System.in);

    long a = sc.nextInt();
    long b = sc.nextInt();
    long c = sc.nextInt();
    long d = sc.nextInt();

    long x = a % d * b % d * c % d;

    System.out.println(x);
  }
}