ارسال شماره 999

import java.util.*;
class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        List<Integer> list = new ArrayList<>();

        for (int i = 0; i < 4; i++) {
            int num = sc.nextInt();
            if (!list.contains(num)) {
                list.add(num);
            }
        }

        System.out.println(list.size()==2? "YES" : "NO");


    }
}