#include "bits/stdc++.h"
using namespace std;
#define rep(i,n) for(int (i)=0;(i)<(int)(n);++(i))
#define rer(i,l,u) for(int (i)=(int)(l);(i)<=(int)(u);++(i))
#define reu(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i))
static const int INF = 0x3f3f3f3f; static const long long INFL = 0x3f3f3f3f3f3f3f3fLL;
typedef vector<int> vi; typedef pair<int, int> pii; typedef vector<pair<int, int> > vpii; typedef long long ll;
template<typename T, typename U> static void amin(T &x, U y) { if(y < x) x = y; }
template<typename T, typename U> static void amax(T &x, U y) { if(x < y) x = y; }

int main() {
	string A, B;
	while(cin >> A >> B) {
		int X = atoi(A.c_str()), Y = atoi(B.c_str());
		bool ans = A == to_string(X) && B == to_string(Y);
		ans &= 0 <= X && X <= 12345;
		ans &= 0 <= Y && Y <= 12345;
		puts(ans ? "OK" : "NG");
	}
	return 0;
}