// This file is a "Hello, world!" in C++ language by GCC for wandbox.
#include <iostream>
#include <cstdlib>

using namespace std;

const int INF = 100100100;

int check(string s){
 if(s[0] == '0' && s.size() >= 2)return INF;
 int num = 0;
 int n = s.size();
 for(int i = 0; i < n; i++){
     if('0' <= s[i] && s[i] <= '9'){
         num += s[i] - '0';
         num *= 10;
     }else{
         return INF;
     }
 }
 num /= 10;
 return num;
}

int main(){
  string a , b;
  cin >> a >> b;
  if(0 <= check(a) && check(a) <= 12345 && 0 <= check(b) && check(b) <= 12345)cout << "OK" << endl;
  else cout << "NG" << endl;
  return 0;
}

// GCC reference:
//   https://gcc.gnu.org/

// C++ language references:
//   https://cppreference.com/
//   https://isocpp.org/
//   http://www.open-std.org/jtc1/sc22/wg21/

// Boost libraries references:
//   https://www.boost.org/doc/