#include "bits/stdc++.h"
using namespace std;
     
#define DEBUG(x) cout<<#x<<": "<<x<<endl;
#define DEBUG_VEC(v) cout<<#v<<":";for(int i=0;i<v.size();i++) cout<<" "<<v[i]; cout<<endl
     
typedef long long ll;
#define vi vector<int>
#define vl vector<ll>
#define vii vector< vector<int> >
#define vll vector< vector<ll> >
#define vs vector<string>
#define pii pair<int,int>
#define pis pair<int,string>
#define psi pair<string,int>
const int inf = 1000000001;
const ll INF = 1e16;
#define MOD 1000000007
#define mod 1000000009
#define pi 3.14159265358979323846
#define Sp(p) cout<<setprecision(15)<<fixed<<p<<endl;
int dx[4] = { 1,0,-1,0 }, dy[4] = { 0,1,0,-1 };
int dx2[8] = { 1,1,0,-1,-1,-1,0,1 }, dy2[8] = { 0,1,1,1,0,-1,-1,-1 };


#include <typeinfo>
int main() {
  string a, b;
  cin >> a >> b;
  for (int i = 0; i < a.size(); i++) {
    if (a[i] < '0' || a[i] > '9') {
      cout << "NG" << endl;
      return 0;
    }
  }
  for (int i = 0; i < b.size(); i++) {
    if (b[i] < '0' || b[i] > '9') {
      cout << "NG" << endl;
      return 0;
    }
  }
  int A = stoi(a);
  int B = stoi(b);
  if (A > 12345 || B > 12345) {
    cout << "NG" << endl;
    return 0;
  }
  string a2 = to_string(A);
  string b2 = to_string(B);
  if (a != a2 || b != b2) {
    cout << "NG" << endl;
    return 0;
  }
  cout << "OK" << endl;
  return 0;
}