/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */


import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.ArrayList;
import java.util.Scanner;

/**
 *
 * @author Juan
 */
class Nodo {

    String nick;
    ArrayList<Nodo> variaciones;

    Nodo(String nick, ArrayList<Nodo> variaciones) {
        this.nick = nick;
        this.variaciones = variaciones;
    }

}

public class HashDiccionario {

    static HashMap<String, Integer> listaDeAlias = new HashMap<String, Integer>();
    static BufferedReader entrada = new BufferedReader(new InputStreamReader(System.in));
    static int aliasGlobal = 0;

    static String retornarAlias(String base, int inicio) {

        String aux = base;
        for (int i = inicio+1; i < 100000; i++) {

            if (!listaDeAlias.containsKey(base + i)) {
                aux = base + i;
                aliasGlobal = i;
                break;
            }

        }
        return aux;
    }

    public static void main(String[] args) throws IOException {

        Scanner entrada = new Scanner(System.in);
        while (entrada.hasNext()) {
            int n = entrada.nextInt();
            listaDeAlias = new HashMap<String,Integer>();
            for (int i = 0; i < n; i++) {

                String alias = entrada.next();

                if (listaDeAlias.containsKey(alias)) {

                    int cantidadDeAlias = listaDeAlias.get(alias);
                    // caso de que no tenga ningun alias conocido

                    String nuevoAlias = retornarAlias(alias, cantidadDeAlias);

                    listaDeAlias.put(alias, aliasGlobal);
                    listaDeAlias.put(nuevoAlias, 0);

                    System.out.println(nuevoAlias);
                    aliasGlobal = 0;

                } else {

                    listaDeAlias.put(alias, 0);
                    System.out.println("OK");

                }
            }

        }

    }

}