#include <iostream>
#include <algorithm>
#include <cstdio>
#include <string>

#define ll long long

using namespace std;

int main(){
  
  string a,b;
  cin>>a>>b;
  
  int err=0;
  for(int i=0;i<a.length();++i){
      if(!i&&a[i]=='0'&&a.length()>1) err=1;
      if(a[i]>58) err=1;
  }
  for(int i=0;i<b.length();++i){
      if(!i&&b[i]=='0'&&b.length()>1) err=1;
      if(b[i]>58) err=1;
  }
  if(atoi(a.c_str())>12345||atoi(b.c_str())>12345) err=1;
 
  if(err) cout<<"NG"<<endl;
  else cout<<"OK"<<endl;

  return 0;
}