#include "bits/stdc++.h"
using namespace std;
#define fastcin {\
    cin.tie(0);\
    ios::sync_with_stdio(false);\
}
#define rep(i, a, b) for(int i = a; i < b; i++)
#define rrep(i, a, b) for(int i = a; i >= b; i--)
#define fore(i, a) for(auto &i:a)
#define print(x) cout << x << "\n"
#define SORT(a, n) sort(a, a+n);
#define REVERSE(a,n) reverse(a,a+n);
#define VSORT(v) sort(v.begin(), v.end());
#define VREVERSE(v) reverse(v.begin(), v.end());
#define MOD 1000000007
#define yes "YES"
#define no "NO"
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vll;

int main() {
    fastcin;
    string a, b;
    cin >> a >> b;
    int alen = a.length(), blen = b.length();
    rep(i, 0, alen) {
        if(a[i]>'9') {
            print("NG");
            return 0;
        }
    }
    rep(i, 0, blen) {
        if(b[i]>'9') {
            print("NG");
            return 0;
        }
    }
    int ai = stoi(a), bi = stoi(b);
    if(ai>12345||bi>12345) {
        print("NG");
        return 0;
    }
    int bufai = ai, bufbi = bi;
    rep(i, 0, alen) {
        if(a=="0") break;
        if(bufai==0) {
            print("NG");
            return 0;
        }
        bufai /= 10;
    }
    rep(i, 0, blen) {
        if(bufbi==0) {
            if(b=="0") break;
            print("NG");
            return 0;
        }
        bufbi /= 10;
    }
    print("OK");
    return 0;
}