import java.util.*;

class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int a = in.nextInt();
        int b = in.nextInt();

        String ans = "YES";

        if(a == b && a != 0 && b != 0) ans = "NO";

        if(a % 2 != 0 && b % 2 != 0)
            if((a-b) % 2 == 0)
                ans = "NO";

        System.out.println(ans);
    }
}