#include <bits/stdc++.h>

using namespace std;


int main() {
    int n, i;
    string str;
    map<string, int> m;
    cin >> n;

    for (i = 1; i <= n; ++i) {
        cin >> str;
        if (m.count(str) > 0) {
            m[str]++;
            cout << str << m[str] << endl;
        } else {
            m[str] = 1;
            cout << "OK" << endl;
        }
    }
    return 0;
}