#include<iostream>
#include<vector>
#include<string>
#include<array>
#include<algorithm>
#include<list>
#include<cmath>
#include<iomanip>
#include<queue>
#include<functional>
#include<climits>
#include<iterator>
#include<unordered_set>
#include<unordered_map>
#include<map>
#include<stack>
#include<set>
#include<sstream>
using namespace std;

const double pi=4*atan(1.0);

constexpr long long mod=static_cast<long long>(1e9+7);

using cWeightEdges=vector<vector<pair<int,int>>>;
using cEdges=vector<vector<int>>;

int main(){
	string A,B;

	cin>>A>>B;
	
	bool ans=true;
	for(const auto& val:A){
		if(!('0' <= val && val <= '9')){
			ans=false;
			break;
		}
	}

	if(ans){
		for(const auto& val:B){
			if(!('0' <= val && val <= '9')){
				ans=false;
				break;
			}
		}
	}

	if(ans){
		bool is_zero_leading=false;
		if(A.size()>1 && (A[0] == '0')){
			is_zero_leading=true;
		}
		if(B.size()>1 && (B[0] == '0')){
			is_zero_leading=true;
		}
		if(is_zero_leading)ans=false;
	}

	if(ans){
		stringstream sstream;
		sstream<<A;
		int x;
		sstream>>x;
		if(!(0<=x && x<=12345))ans=false;
	}
	if(ans){
		stringstream sstream;
		sstream<<B;
		int x;
		sstream>>x;
		if(!(0<=x && x<=12345))ans=false;
	}

	if(ans)cout<<"OK"<<endl;
	else cout<<"NG"<<endl;
	//system("pause");
	return 0;
}