import java.util.*;

class HashNode<T>{
    T object;
    String key;

    HashNode(String s,T o){
    this.object = o;
    this.key = s;
    }
}

class HashTable{
    HashNode[] Table;
    int size;

    HashTable(int initial){
        this.size = initial;
        this.Table = new HashNode[initial];
    }

    HashTable(){
        this(9151);
    }

    public int hashCode(String S){
        int hash = 7;
        for (int i = 0; i < S.length(); i++) {
            hash = hash*31 + S.charAt(i);
        }
        return hash;
    }

    public int hashKey(String S){
        return (((this.hashCode(S) & (0x7fffffff)) + 3) % this.size);
    }

    public int hashKey(int I){
        return ((I + 3) % this.size);
    }

    void add(HashNode node){
        int k = hashKey(node.key);
        int i = 0;
        if(Table[k] == null){
            Table[k] = node;
            System.out.println("OK");
        }else{
            while(Table[k] != null){
                i++;
                k = hashKey("" + node.key + String.valueOf(i));
            }
            node.object = (String) ("" + node.key + String.valueOf(i));
            node.key = (String) ("" + node.key + String.valueOf(i));
            Table[k] = node;
            System.out.println(node.object);
        }
    }
}

public class TestClass {

	public static void main(String[] args){
            Scanner sc = new Scanner(System.in);
            while(sc.hasNext()){
                int tc = sc.nextInt();
                HashTable T = new HashTable(21474837);
                for(int i = 0; i < tc; i++){
                    String st = sc.next();
                    HashNode N = new HashNode(st,st);
                    T.add(N);
                }
            }
	}
}