import java.util.*;

/**
 *
 * @author Usuario
 */
public class P104 {

    Scanner in;
    int suma = 0;

    public boolean hayEquilibrio(int pi, int di, int pd, int dd) {
        boolean izqOk = true;
        boolean dchaOk = true;
        if (pi != 0 && dd != 0) {
            if ((pi * di) == (pd * dd)) {
                suma = pi + pd;
                return true;
            }
            return false;
        }
        if (pi == 0) {
            int pi2 = in.nextInt();
            int di2 = in.nextInt();
            int pd2 = in.nextInt();
            int dd2 = in.nextInt();
            izqOk = hayEquilibrio(pi2, di2, pd2, dd2);
            pi = suma;
        }
        if (pd == 0) {
            int pi2 = in.nextInt();
            int di2 = in.nextInt();
            int pd2 = in.nextInt();
            int dd2 = in.nextInt();
            dchaOk = hayEquilibrio(pi2, di2, pd2, dd2);
            pd = suma;
        }
        suma = pi + pd;
        return izqOk && dchaOk && pi * di == pd * dd;
    }

    public boolean caso() {
        int pi = in.nextInt();
        int di = in.nextInt();
        int pd = in.nextInt();
        int dd = in.nextInt();
        if (pi == 0 && di == 0 && pd == 0 && dd == 0) {
            return false;
        }
        System.out.println(hayEquilibrio(pi, di, pd, dd) ? "SI" : "NO");
        return true;
    }

    public void run() {
        in = new Scanner(System.in);
        while (caso());
    }

    public static void main(String[] args) {
        new P104().run();
    }
}