#include<bits/stdc++.h>
using namespace std;

bool solver(string s){
    int a=0,p=1;
    for(int i=0;i<s.size()-1;i++) p*=10;
    for(int i=0;i<s.size();i++){
        int tmp=s[i]-'0';
        if(tmp>=0&&tmp<=9){
            if(a==0&&tmp==0&&s.size()!=1) return false;
            a+=p*(tmp);
            p/=10;
        }else return false;
    }
    if(a>12345) return false;
    return true;
}

int main(){
    string s1,s2;
    cin >> s1 >> s2;
    
    if(solver(s1)&&solver(s2)) cout << "OK" << endl;
    else cout << "NG" << endl;

    return 0;
}