#include<bits/stdc++.h>
using namespace std;

bool check(string s){
  if(s=="0")return true;
  if(s[0]=='0')return false;
  for(char ch:s){
    if('0'<=ch&&ch<='9'){
    }else{
      return false;
    }
  }

  int num;
  stringstream ss;
  ss<<s;
  ss>>num;

  return (0<=num && num<= 12345);
}

int main(){
  string A,B;
  cin>>A>>B;
  if(check(A)&&check(B))cout<<"OK"<<endl;
  else cout<<"NG"<<endl;
}