#include <bits/stdc++.h>

using namespace std;

#define REP(i,n) for(int i=0; i<(int)(n); i++)

bool check(const string &s) {
  for (char c: s)
    if (!isdigit(c))
      return false;
  if (s.length() > 1 && s[0] == '0')
    return false;

  int x = stoi(s);
  return 0 <= x && x <= 12345;
}

int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);

  string a, b;
  cin >> a >> b;

  if (check(a) && check(b))
    cout << "OK" << endl;
  else
    cout << "NG" << endl;
  
  return 0;
}