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

#define FOR(i,l,r) for(int i = (l);i < (r);i++)
#define ALL(x) (x).begin(),(x).end()
template<typename T> bool chmax(T& a,const T& b){return a < b ? (a = b,true) : false;}
template<typename T> bool chmin(T& a,const T& b){return b < a ? (a = b,true) : false;}
typedef long long ll;

int N,M;
string A,B;

int main()
{
	cin.tie(nullptr);
	ios::sync_with_stdio(false);

	cin >> A >> B;
	N = A.size(); M = B.size();

	bool ok = true;
	FOR(i,0,N){
		if(A [i] < '0' || '9' < A [i]){
			ok = false;
		}
	}
	FOR(i,0,M){
		if(B [i] < '0' || '9' < B [i]){
			ok = false;
		}
	}

	if(A.front() == '0' && N != 1){
		ok = false;
	}
	if(B.front() == '0' && M != 1){
		ok = false;
	}
	if(ok && (stoi(A) < 0 || stoi(A) > 12345)){
		ok = false;
	}
	if(ok && (stoi(B) < 0 || stoi(B) > 12345)){
		ok = false;
	}

	cout << (ok ? "OK" : "NG") << endl;

	return 0;
}