#include <iostream>
#include <sstream>
#include <cstdlib>
#include <algorithm>
#include <cmath>
#include <iomanip>
#include <numeric>
#include <vector>
#include <string>
#include <set>
#include <map>
#include <deque>
using namespace std;
#define ll long long

void sherry()
{
    ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
#ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout);
#endif
}
/*bool comp(pair <string,int> a,pair<string,int> b){
    return a.second < b.second;
}*/
int main()
{
    sherry();
    ll t;
    cin >> t;
    map<string, ll> m;
    for (ll i = 0; i < t; i++)
    {
        string g;
        cin >> g;
        if (m.find(g) != m.end())
        {
            cout << g << m.count(g) << endl;
        }
        else
        {
            cout << "OK\n";
        }
        m[g]++;
    }
    return 0;
}