/******************************************************************************
 
                              Online C++ Compiler.
               Code, Compile, Run and Debug C++ program online.
Write your code in this editor and press "Run" button to compile and execute it.
 
*******************************************************************************/
 
#include<bits/stdc++.h>
 
using namespace std;
int main(){
map < string, int >m;
int n;
cin >> n;
 
while (n-- > 0)
  {
    string s;
    cin >> s;
    if (m[s] == 0)
      {
	cout << "OK" << endl;
	m[s]++;
      }
    else
      {
 
	cout << s << m[s] << endl;
	m[s]++;
      }
 
  }
 
return 0;
}
 

LyoqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKgoKICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgT25saW5lIEMrKyBDb21waWxlci4KICAgICAgICAgICAgICAgQ29kZSwgQ29tcGlsZSwgUnVuIGFuZCBEZWJ1ZyBDKysgcHJvZ3JhbSBvbmxpbmUuCldyaXRlIHlvdXIgY29kZSBpbiB0aGlzIGVkaXRvciBhbmQgcHJlc3MgIlJ1biIgYnV0dG9uIHRvIGNvbXBpbGUgYW5kIGV4ZWN1dGUgaXQuCgoqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqKioqLwoKI2luY2x1ZGU8Yml0cy9zdGRjKysuaD4KCnVzaW5nIG5hbWVzcGFjZSBzdGQ7CmludCBtYWluKCl7Cm1hcCA8IHN0cmluZywgaW50ID5tOwppbnQgbjsKY2luID4+IG47Cgp3aGlsZSAobi0tID4gMCkKICB7CiAgICBzdHJpbmcgczsKICAgIGNpbiA+PiBzOwogICAgaWYgKG1bc10gPT0gMCkKICAgICAgewoJY291dCA8PCAiT0siIDw8IGVuZGw7CgltW3NdKys7CiAgICAgIH0KICAgIGVsc2UKICAgICAgewoKCWNvdXQgPDwgcyA8PCBtW3NdIDw8IGVuZGw7CgltW3NdKys7CiAgICAgIH0KCiAgfQoKcmV0dXJuIDA7Cn0K

NgpmaXJzdApmaXJzdApzZWNvbmQKc2Vjb25kCnRoaXJkCnRoaXJk

6
first
first
second
second
third
third