#include <cstdio>
#include <string>
#include <iostream>
#include <algorithm>
 
 
using namespace std;
#define MAXN  ('z'-'a'+2)
#define VALUE(c) ( (c)-'a' )
 
struct Trie
{
	Trie *m[MAXN];
	int count;
}trie;
 
int insert(Trie *  t, char * w){
	if(w[0]=='\0'){
		t->count++;
		return t->count;
	}
	if(t->m[VALUE(w[0])] == NULL){
		t->m[VALUE(w[0])] =(Trie *) malloc(sizeof(Trie));
	}
	return insert(t->m[VALUE(w[0])] , w+1);
}	
 
 
int main(){
 
	int t;
	scanf("%d",&t);
 
	for (int i = 0; i < t; ++i)
	{
		char *w = NULL;
	    w = (char *)malloc(sizeof(char));
	    scanf("%s",w);
	    //printf("%s\n", w);
		int resp = insert(&trie,w);	
		if(resp > 1){
			printf("%s%d\n", w,resp-1);
		}else{
			printf("OK\n");
		}
	}
 
 
	return 0;
 
}

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