import java.util.Scanner;

public class Test {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		long a, b, c, d, e;
		a = sc.nextLong();
		b = sc.nextLong();
		c = sc.nextLong();
		d = sc.nextLong();
		a %= d;
		b %= d;
		c %= d;
		a *= b;
		a %= d;
		a *= c;
		a %= d;
		System.out.println(a);
	}
}