#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;
typedef long long ll;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);
    
    string A,B; cin >> A >> B;
    auto f = [&](string X) {
        for(char c : X) if(!isdigit(c)) return false;
        if(X.size() >= 2u && X[0] == '0') return false;
        int x = stoi(X);
        return 0 <= x && x <= 12345;
    };

    cout << (f(A) && f(B) ? "OK" : "NG") << endl;
}