#include <iostream>
#include <string>
#include <stdexcept>
using namespace std;
int main(void){
    // Here your code !
    string a,b;
    cin >> a >> b;
    try{
    stoi(a,nullptr,10);
    stoi(b,nullptr,10);
    
    if( a[0] == '0' && a.size() != 1){
        if( b[0] == '0' && b.size() != 1){
            cout << "NG" << endl;
        }else{
            cout << "OK" << endl;
        }
    }else{
        cout << "OK" << endl;
    }
        
    }catch(const std::logic_error& e){
        cout << "NG" << endl;
    }
}