import java.math.BigInteger;
import java.util.Scanner;

public class a {
	public static void main(String args[]){
		Scanner sc = new Scanner(System.in);
		BigInteger a = sc.nextBigInteger();
		BigInteger b = sc.nextBigInteger();
		BigInteger c = sc.nextBigInteger();
		BigInteger d = sc.nextBigInteger();
		BigInteger foo = a.multiply(b).mod(d).multiply(c).mod(d);
		System.out.println(foo.toString());
	}
}