/* -*- coding: utf-8 -*-
 *
 * 446.cc: No.446 ゆきこーだーの雨と雪 (1) - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

/* typedef */

/* global variables */

/* subroutines */

int s2num(string &s) {
  if (s.size() > 1 && s[0] == '0') return -1;
  int n = 0;
  for (int i = 0; i < s.size(); i++) {
    if (s[i] < '0' || s[i] > '9') return -1;
    n = 10 * n + s[i] - '0';
  }
  return n;
}

/* main */

int main() {
  string sa, sb;
  cin >> sa >> sb;

  int a = s2num(sa), b = s2num(sb);

  if (a >= 0 && a <= 12345 && b >= 0 && b <= 12345) puts("OK");
  else puts("NG");
  return 0;
}