#include <bits/stdc++.h>
using namespace std;
/*{{{*/  //template
#define REP(i,n) for(int i=0;i<n;i++)
#define rep(i,n) for(int i=0;i<n;i++)
#define INF 1<<29
#define LINF LLONG_MAX/3
#define MP make_pair
#define PB push_back
#define EB emplace_back
#define ALL(v) (v).begin(),(v).end()
#define all(v) ALL(v)
#define debug(x) cerr<<#x<<":"<<x<<endl
#define debug2(x,y) cerr<<#x<<","<<#y":"<<x<<","<<y<<endl
#define CININIT cin.tie(0),ios::sync_with_stdio(false)
template<typename T> ostream& operator<<(ostream& os,const vector<T>& vec){ os << "["; for(const auto& v : vec){ os << v << ","; } os << "]"; return os; }
template<typename T,typename U> ostream& operator<<(ostream& os,const pair<T,U>& p){ os << "(" << p.first << ","<< p.second <<")"; return os; }
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;
ll gcd(ll a,ll b){ if(b==0) return a; else return gcd(b,a%b); }

constexpr ll mod = 1e9+7;
const int dx[]={1,0,-1,0} ,dy[] = {0,1,0,-1};
/*}}}*/

int main(){
    string A,B;
    cin>>A>>B;


    if((A[0]=='0' and A!="0") or (B[0]=='0' and B!="0")){
            cout << "NG" << endl;
            return 0;
    }


    for(char a:A){
        int aa = a-'0';
        if(!(0<=aa and aa<=9)){
            cout << "NG" << endl;
            return 0;
        }
    }
    for(char a:B){
        int aa = a-'0';
        if(!(0<=aa and aa<=9)){
            cout << "NG" << endl;
            return 0;
        }
    }

    if(stoi(A)>12345 or stoi(B)>12345){
            cout << "NG" << endl;
            return 0;

    }
    cout << "OK" << endl;
}