#include<bits/stdc++.h>
#include <cmath>
using namespace std;

/* 1 x y
 * 2 x */

int main() {
 ios_base::sync_with_stdio(false);
 cin.tie(NULL);
 cout.tie(NULL);;

 int n;
 cin>>n;
 map <string, int> mp;
 for(int i=0;i<n;i++) {
  string s;
  cin>>s;
  if (mp[s]==0) {
   cout<<"OK\n";
   mp[s]=1;
  }
  else {

   cout<<s<<mp[s]<<"\n";
   mp[s]++;
  }
 }



 return 0;
}