#include <bits/stdc++.h>
using namespace std;
#define GG ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
int main () { GG;
int n; string x;
cin>>n;
map<string,int> m;
for(int i=0;i<n;i++)
{ cin>>x;
if(m.count(x))
{ cout<<x<<m[x]<<"\n";
m[x]++;
}
else
{ m.insert({x,1});
cout<<"OK\n";
}
}
return 0;}
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