#include <bits/stdc++.h> using namespace std; int main() { int a, b; while (cin >> a >> b) { // 注意 while 处理多个 case int a1 = 0, b1 = 0, sum = a + b; while (a) { a1 = a1 * 10 + a % 10; a /= 10; } while (b) { b1 = b1 * 10 + b % 10; b /= 10; } a1 += b1; b1 = 0; while (a1) { b1 = b1 * 10 + a1 % 10; a1 /= 10; } if (b1 == sum) { cout << sum << endl; } else { cout << "NO" << endl; } } } // 64 位输出请用 printf("%lld")