import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

import static java.lang.System.in;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(in));
        String[] inputs = reader.readLine().split(" ");
        long H = Long.parseLong(inputs[0]);
        long W = Long.parseLong(inputs[1]);
        long N = Long.parseLong(inputs[2]);
        long K = Long.parseLong(inputs[3]);
        if((H*W)%N == K%N) {
            System.out.println("YES");
        } else {
            System.out.println("NO");
        }
    }
}