#include<iostream>
#include <string>
#include <stdlib.h>

using namespace std;

int main(){
  string s1,s2;
  cin >> s1 >> s2;
  char * endpos1,*endpos2;
  strtoll(s1.c_str(),&endpos1,10);
  strtoll(s2.c_str(),&endpos2,10);
  if(*endpos1!= '\0' || *endpos2!='\0'){
    cout <<"NG"<<endl;
  }else{
    cout <<"OK"<<endl;
  }
}