#include <iostream>
#include<string>
#include<vector>
#include<algorithm>
using namespace std;
#define REP(i,n) for(int i=0;i<n;i++)
int main(){
cin.tie(0);
ios::sync_with_stdio(false);

	string A,B;
	cin>>A>>B;
	if(A[0]=='0'){
		if(A[1]!=NULL){
			cout<<"NG"<<endl;
			return 0;
		}
	}
	if(B[0]=='0'){
		if(B[1]!=NULL){
			cout<<"NG"<<endl;
			return 0;
		}
	}

	REP(i,A.size()){
		if(A[i]>=65 && A[i]<=90){
			cout<<"NG"<<endl;
			return 0;
		}
		if(A[i]>=97 && A[i]<=122){
			cout<<"NG"<<endl;
			return 0;
		}
	}
	REP(i,B.size()){
		if(B[i]>=65 && B[i]<=90){
			cout<<"NG"<<endl;
			return 0;
		}
		if(B[i]>=97 && B[i]<=122){
			cout<<"NG"<<endl;
			return 0;
		}
	}
	if(A[4]!=NULL){
		int a=A[0]*10000+A[1]*1000+A[2]*100+A[3]*10+A[4]*1;
		if(a>12345){
			cout<<"NG"<<endl;
			return 0;
		}
	}
	if(B[4]!=NULL){
		
		int b=B[0]*10000+B[1]*1000+B[2]*100+B[3]*10+B[4]*1;
		if(b>12345){
			cout<<"NG"<<endl;
			return 0;
		}
	}
		cout<<"OK"<<endl;
	
	return 0;
}