#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <utility>
#include <stack>
#include <functional>
#include <queue>
#include <cmath>
#include <set>

#define rep(i,j,k) for(int i=j;i<k;i++)
#define drep(n,m) for(int i=0;i<n;i++)for(int j=0;j<m;j++)
#define Sort(x) sort((x).begin(),(x).end())
#define fi first
#define se second
#define vi vector<int>
#define INF 1000000000
#define MOD 1000000009
#define pb push_back
#define mp make_pair
typedef long long ll;
typedef unsigned long long ull;
int dx[4]={0,1,0,-1},dy[4]={1,0,-1,0};

using namespace std;

ll gcd(ll a,ll b){
    if(a<b){
        int t=a;a=b;b=t;
    }
    int c=a%b;
    while(c!=0){
        a=b;
        b=c;
        c=a%b;
    }
    return b;
}

ll lcm(ll a,ll b){
    return a*b/gcd(a,b);
}

bool isPrime(int x){
    if(x==1)return false;
    if(x==2)return true;
    if(x%2==0)return false;
    for(int i=3;i<=sqrt(x);i+=2){
        if(x%i==0)return false;
    }
    return true;
}

int kaizyo(int x){
    if(x==1)return x;
    else return x*kaizyo(x-1);
}

typedef struct Point{
    int x;
    int y;
} P;


int main() {
    string s,ss;
    cin>>s>>ss;
    rep(i,0,s.length()){
        if('0'<=s[i]&&s[i]<='9')continue;
        else {
            cout<<"NG"<<endl;
            return 0;
        }
    }
    rep(i,0,ss.length()){
        if('0'<=ss[i]&&ss[i]<='9')continue;
        else {
            cout<<"NG"<<endl;
            return 0;
        }
    }
    if((s.length()!=1&&s[0]=='0')||(ss.length()!=1&&ss[0]=='0')){
        cout<<"NG"<<endl;
        return 0;
    }
    
    if(stoi(s)>12345 || stoi(ss)>12345 || stoi(s)<0||stoi(ss)<0){
        cout<<"NG"<<endl;
        return 0;
    }
    cout<<"OK"<<endl;
    return 0;
}