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

typedef tuple< int, int, char > height;

int main(void)
{
  string a, b;
  cin >> a >> b;
  if (a.size()<=5 && b.size()<=5) {
    if ((a.size()>=2 && a[0]=='0') || (b.size()>=2 && b[0]=='0')) {cout << "NG" << endl; return 0;}
    for (int i = 0; i < a.size(); ++i) {
      if (a[i] < '0' || '9' < a[i]) {cout << "NG" << endl; return 0;}
    }
    for (int i = 0; i < b.size(); ++i) {
      if (b[i] < '0' || '9' < b[i]) {cout << "NG" << endl; return 0;}
    }
    int a_int = stoi(a), b_int = stoi(b);
    if (0 <= a_int && a_int <= 12345 && 0 <= b_int && b_int <= 12345) {
      cout << "OK" << endl;
      return 0;
    }
  }
  cout << "NG" << endl;
  return 0;
}