#include <bits/stdc++.h>
using namespace std;

int main(void) {
	string a, b;
	cin>>a>>b;
	if(a[0]=='0'||b[0]=='0'){cout<<"NG"<<endl;return 0;}
	   string str(a);
	    int num = std::atoi(str.c_str());
	    if(num>12345){
			cout<<"NG"<<endl;
			return 0;
	    }

	    string strb(b);
	    	    int numb = std::atoi(strb.c_str());
	    	    if(numb>12345){
	    			cout<<"NG"<<endl;
	    			return 0;
	    	    }

	for (int i = 0; i < a.length(); ++i) {

		if(a[i]>=48&&a[i]<=57){

		}else{
		cout<<"NG"<<endl;
		return 0;
		}
	}
	for (int i = 0; i < b.length(); ++i) {
		if(b[i]>=48&&b[i]<=57){

		}else{
		cout<<"NG"<<endl;
		return 0;
		}
	}
	cout<<"OK"<<endl;
}