#include <iostream> using namespace std; int reverse(int n) { int t = n; int count = 0; while (t) { count++; t /= 10; } int a[count]; t = n; for (int i = count - 1; i >= 0; i--) { a[i] = t % 10; t /= 10; } int res = 0; for (int i = count - 1; i >= 0; i--) { res += a[i]; res *= 10; } return res / 10; } int main() { int n1, n2; int r1, r2; while (cin >> n1 >> n2) { r1 = n1 + n2; r2 = reverse(n1) + reverse(n2); if (r1 == reverse(r2)) { cout << r1 << endl; } else { cout << "NO" << endl; } } } // 64 位输出请用 printf("%lld")