#include<bits/stdc++.h>

using namespace std;
using ll=long long;
#define rep2(i, a, n) for(int i = (a); i < (n); i++)
#define rep(i, n) rep2(i,0,n)

int main(){
  cin.tie(nullptr);ios_base::sync_with_stdio(false);
  string a,b;cin>>a>>b;
  rep(i,a.size()){
    if(a[i]<'0'||a[i]>'9'){
      cout<<"NG"<<endl;
      return 0;
    }
  }
  rep(i,b.size()){
    if(b[i]<'0'||b[i]>'9'){
      cout<<"NG"<<endl;
      return 0;
    }
  }
  if(a.size()>1 && a[0]=='0'||b.size()>1 &&b[0]=='0'||stoi(a)>12345||stoi(b)>12345){
    cout<<"NG"<<endl;
    return 0;
  }
  cout<<"OK"<<endl;
}