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

bool ok(string s) {
    if(s[0] == '0' && s.size() >= 2) return false;
    for(char c : s) {
        if(!('0' <= c && c <= '9')) return false;
    }
    return stoi(s) <= 12345;
}
string s, t;
int main() {
    cin >> s >> t;
    cout << (ok(s) && ok(t) ? "OK" : "NG") << endl;
}