#include <bits/stdc++.h>
#include <typeinfo>
#include <cxxabi.h>
#ifdef LOCAL
#include "dbgtoki.hpp"
#define DUMP(i) dump((string)TOSTRING(i), demangle(typeid(i).name()), __LINE__ , i) 
#else
#define DUMP(i)
#endif

using namespace std;
#define TOSTRING(x) #x
#define SZ(x) (int)(x).size()
#define REP(i,n) for(int i=0;i<(n);i++)
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define ALL(s) (s).begin(), (s).end()
#define UNIQUE(v) v.erase( unique(v.begin(), v.end()) , v.end());
#define dis distance
#define so(V) sort(ALL(V))
#define rev(V) reverse(ALL(V))
#define pub push_back
#define sec second
#define fir first

typedef long long unsigned int llu;
typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<vector <int> > vvi;
const int EPS = 1e-9;
const int MOD = 1e9+7;
const int INF = (1 << 30);

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);
	string a,b;
	cin >> a >> b;
	stringstream ssa;
	stringstream ssb;
	if(SZ(a) > 5 || SZ(b) > 5){
		cout << "NG" << endl;
		return 0;
	}
	bool isFirst = true;
	REP(i,SZ(a)){
		if(isFirst && (i != SZ(a)-1)&&(a[i] == '0')){
			cout << "NG" << endl;
			return 0;
		}else if(a[i] - '0' < 0 || a[i] - '0' > 9){
			cout << "NG" << endl;
			return 0;
		}else isFirst = false;
	}
	isFirst = true;
	REP(i,SZ(b)){
		if(isFirst && (i != SZ(b)-1)&&(b[i] == '0')){
			cout << "NG" << endl;
			return 0;
		}else if(b[i] - '0' < 0 || b[i] - '0' > 9){
			cout << "NG" << endl;
			return 0;
		}else isFirst = false;
	}
	ssa << a;
	ssb << b;
	int ia,ib;
	ssa >> ia;
	ssb >> ib;
	if(ia > 12345 || ib > 12345){
		cout << "NG" << endl;
	}else{
		cout << "OK" << endl;
	}
	return 0;
}