using System;
using System.Collections.Generic;

namespace Задачи_CodeForces
{
    class Program
    {
        static void Main(string[] args)
        {
            Dictionary<string, int> archive = new Dictionary<string, int>();
            int linesCount = int.Parse(Console.ReadLine());
            for (int i = 0; i < linesCount; i++)
            {
                string temp = Console.ReadLine();
                if (archive.ContainsKey(temp))
                {
                    string newName = temp + archive[temp]++;
                    archive.Add(newName, 1);
                    Console.WriteLine(newName);
                }
                else
                {
                    archive.Add(temp, 1);
                    Console.WriteLine("OK");
                }
            }
        }
    }
}