7:2

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int n;
    cin>>n;
    vector<string>v(n);
    for(int i=0;i<n;i++)
    {
        cin>>v[i];
    }
    map<string,int>mp;
    for(auto u:v)
    {
        if(mp[u]==0) cout<<"OK\n";
        else cout<<u<<mp[u]<<endl;
        mp[u]++;
    }
}