#include "bits/stdc++.h"
using namespace std;
#define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i))
#define rep(i,j) FOR(i,0,j)
#define each(x,y) for(auto &(x):(y))
#define mp make_pair
#define mt make_tuple
#define all(x) (x).begin(),(x).end()
#define debug(x) cout<<#x<<": "<<(x)<<endl
#define smax(x,y) (x)=max((x),(y))
#define smin(x,y) (x)=min((x),(y))
#define MEM(x,y) memset((x),(y),sizeof (x))
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;

int f(string s) {
    if(sz(s) > 1 && s[0] == '0')return 0;
    each(c, s)if(!('0'<=c&&c<='9'))return 0;
    if(sz(s) > 5)return 0;
    ll x = stoll(s);
    if(x < 0 || x > 12345)return 0;
    return 1;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    string s, t;
    while(cin >> s >> t) {
        if(f(s) && f(t)) {
            
            cout << "OK" << endl;
        } else {
            cout << "NG" << endl;
        }
    }
}