#include <bits/stdc++.h>
using namespace std;
#define int long long
signed main(){
  set<string> s;
  for(int i=0;i<=12345;i++){
      s.insert(to_string(i));
  }
  string a,b;
  cin>>a>>b;
  if(s.count(a) && s.count(b)) cout<<"OK"<<endl;
  else cout<<"NG"<<endl;
}