#include<iostream>
#include<string>
#include<unordered_set>
using namespace std;

int main () {
    string s;
    while (getline(cin, s)) {
        // 要求1
        int len = s.size();
        if (len <= 8) {
            cout << "NG" << endl;
            continue;
        }
        // 要求2
        unordered_set<int> set;
        for (int i = 0; i < len; ++i) {
            if (s[i] >= 'A' && s[i] <= 'Z')
                set.insert(1);
            else if (s[i] >= 'a' && s[i] <= 'z')
                set.insert(2);
            else if (s[i] >= '0' && s[i] <= '9')
                set.insert(3);
            else
                set.insert(4);
        }
        if (set.size() < 3) {
            cout << "NG" << endl;
            continue;
        }
        // 要求3
        int flag = 0;
        for (int i = 0; i < len - 3; ++i) {
            for (int j = i + 1; j < len - 2; ++j) {
                if (s.substr(i, 3) == s.substr(j, 3)) {
                    flag = 1;
                    break;
                }
            }
            if (flag == 1)
                break;
        }
        if (flag == 1) {
            cout << "NG" << endl;
            continue;
        }

        cout << "OK" << endl;

    }


    return 0;
}