import java.util.Scanner;

class Main {
    public static void main(String[] args) throws Exception {
        Scanner in = new Scanner(System.in);
        int h = in.nextInt();
        int w = in.nextInt();
        int n = in.nextInt();
        int k = in.nextInt();

        if((h*w) % k == 0) {
            System.out.println("NO");
        } else {
            System.out.println("YES");
        }
    }
}