#include <iostream>
#include <algorithm>

using namespace std;

// 反转整数
int reverseInt(int num) {
    string str = to_string(num);
    reverse(str.begin(), str.end());
    return stoi(str);
}

int main() {
    int a, b;
    while (cin >> a >> b) {  // 读取多组数据
        int sum = a + b;
        int revA = reverseInt(a);
        int revB = reverseInt(b);
        int revSum = reverseInt(sum);

        if (revSum == revA + revB) 
            cout << sum << endl;
        else 
            cout << "NO" << endl;
    }
    return 0;
}