#include <bits/stdc++.h>
using namespace std;

int main() {
  string S, T = "OK";
  while (cin >> S) {
    for (char c : S) if (!isdigit(c)) return cout << "NG" << "\n", 0;
    if (S.size() > 1 && S.at(0) == '0' || stoi(S) > 12345) T = "NG";
  }
  cout << T << "\n";
}