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

#define int long long
typedef vector<int>vint;
typedef pair<int,int>pint;
typedef vector<pint>vpint;
#define rep(i,n) for(int i=0;i<(n);i++)
#define reps(i,f,n) for(int i=(f);i<(n);i++)
#define all(v) (v).begin(),(v).end()
#define each(it,v) for(__typeof((v).begin()) it=(v).begin();it!=(v).end();it++)
#define pb push_back
#define fi first
#define se second
template<typename A,typename B>inline void chmin(A &a,B b){if(a>b)a=b;}
template<typename A,typename B>inline void chmax(A &a,B b){if(a<b)a=b;}

signed main(){
    string A,B;
    cin>>A>>B;
    bool ok=true;
    rep(i,A.size())if(!isdigit(A[i]))ok=false;
    rep(i,B.size())if(!isdigit(B[i]))ok=false;

    stringstream ss;
    ss<<A;int a;ss>>a;
    ss.clear();
    ss<<B;int b;ss>>b;
    if(!ok||a<0||a>12345||b<0||b>12345||(A.size()>1&&A[0]=='0')||(B.size()>1&&B[0]=='0')){
        cout<<"NG"<<endl;
    }
    else{
        cout<<"OK"<<endl;
    }
    return 0;
}