#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i, n) for(ll i = 0, i##_len = (n); i < i##_len; i++)
#define reps(i, s, n) for(ll i = (s), i##_len = (n); i < i##_len; i++)
#define rrep(i, n) for(ll i = (n) - 1; i >= 0; i--)
#define rreps(i, e, n) for(ll i = (n) - 1; i >= (e); i--)
#define all(x) (x).begin(), (x).end()
#define sz(x) ((ll)(x).size())
#define len(x) ((ll)(x).length())

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    // ifstream in("input.txt");
    // cin.rdbuf(in.rdbuf());
    string a, b;
    cin >> a >> b;
    rep(i, len(a)) {
        if (
            ((a[i] < '0') || (a[i] > '9')) ||
            ((i == 0) && (len(a) > 1) && (a[i] == '0'))
        ) {
            cout << "NG" << endl;
            return 0;
        }
    }
    rep(i, len(b)) {
        if (
            ((b[i] < '0') || (b[i] > '9')) ||
            ((i == 0) && (len(b) > 1) && (b[i] == '0'))
        ) {
            cout << "NG" << endl;
            return 0;
        }
    }
    ll va = atoi(a.c_str()), vb = atoi(b.c_str());
    if ((va > 12345) || (vb > 12345)) {
        cout << "NG" << endl;
        return 0;
    }
    cout << "OK" << endl;
    return 0;
}