import java.util.Scanner;

class no166{
	public static void main(String[] args) {
		Scanner stdIn=new Scanner(System.in);
		long h=stdIn.nextLong(),w=stdIn.nextLong(),n=stdIn.nextLong(),k=stdIn.nextLong();
		System.out.print(h*w-h*w/n*n==k||h*w%n==0&&n==k?"YES":"NO");
	}
}