#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using ld = long double;

string a, b;

int main() {
  cin >> a >> b;
  for (int i = 0; i < a.size(); i++) {
    if (!isdigit(a[i])) {
      cout << "NG" << endl;
      return 0;
    }
  }
  for (int i = 0; i < b.size(); i++) {
    if (!isdigit(b[i])) {
      cout << "NG" << endl;
      return 0;
    }
  }
  ll A = stoll(a), B = stoll(b);
  if (a == to_string(A) && b == to_string(B)) {
    if (0 <= A && A <= 12345 && 0 <= B && B <= 12345) {
      cout << "OK" << endl;
      return 0;
    }
  } 
  cout << "NG" << endl;
  return 0;
}