#include <iostream> using namespace std; int main() { string x, y; while (cin >> x >> y) { if (x == "0" && y == "0") break; else { int res = 0, t = 0; for (int i = x.size() - 1, j = y.size() - 1; i >= 0 || j >= 0; i--, j--) { if (i >= 0) t += x[i] - '0'; if (j >= 0) t += y[j] - '0'; t /= 10; //向高位进位 if (t > 0) { res++;//记录进位次数 } } if (res == 0) cout << "NO carry operation." << endl; else if (res == 1) cout << "1 carry operation." << endl; else cout << res << " carry operations." << endl; } } return 0; }