#include <iostream>
#include <string>
using namespace std;
bool NotDigit(string S){
	for (int i=0;i<S.length();i++){
		if (S[i]<'0' || S[i]>'9'){
			return true;
		}
	}
	return false;
}
int main(int argc, char* argv[])
{
	string A,B;
	cin>>A;
	cin>>B;
	if (NotDigit(A) || NotDigit(B)){
		cout<<"NG"<<endl;
		return 0;
	}
	int a1=atol(A.c_str());
	int b1=atol(B.c_str());
	if (a1>12345 || b1>12345){
		cout<<"NG"<<endl;
		return 0;
	}
	if (a1>0 && A[0]=='0' || b1>0 && B[0]=='0'){
		cout<<"NG"<<endl;
		return 0;	
	}
	cout<<"OK"<<endl;
	return 0;
}