import java.util.Scanner;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner koko = new Scanner (System.in);
        int h = koko.nextInt();
        int w = koko.nextInt();
        int n = koko.nextInt();
        int k = koko.nextInt();
        int mass = h*w;
        if(n!=k){
            if(mass%n==k){
                System.out.println("YES");
            }else{
                System.out.println("NO");
            }
        }
        if(n==k){
            if(mass%n==0){
                System.out.println("YES");
            }else{
                System.out.println("NO");
            }
        }
    }
}