#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
#define yn {puts("OK");}else{puts("NG");}
#define MAX_N 200005

int main() {
    string s, t;
    cin >> s >> t;
    int n = s.size();
    int m = t.size();

    int flag = 1;
    rep(i,n){
        if(s[i] < '0' || '9' < s[i])flag = 0;
    }
    rep(i,m){
        if(t[i] < '0' || '9' < t[i])flag = 0;
    }

    int flag2 = 0;
    rep(i,n){
        if(n == 1)break;
        if(s[i] != '0')flag2 = 1;
        else if(flag2 == 0)flag = 0;
    }
    flag2 = 0;
    rep(i,m){
        if(m == 1)break;
        if(t[i] != '0')flag2 = 1;
        else if(flag2 == 0)flag = 0;
    }
   
    if(n == 5 && s > "12345")flag = 0;
    if(m == 5 && t > "12345")flag = 0;

    if(flag)yn;
    return 0;
}