codeforces 4C Registration system

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <ctype.h>
#include <math.h>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <vector>
#include <string>
#include <iostream>
#include <algorithm>
using namespace std;
#define ll long long
#define ls rt<<1
#define rs ls1
#define lson l,mid,ls
#define rson mid+1,r,rs
#define middle (l+r)>>1
#define eps (1e-9)
#define clr_all(x,c) memset(x,c,sizeof(x))
#define clr(x,c,n) memset(x,c,sizeof(x[0])*(n+1))
#define MOD 1000000007
#define inf 100000007
#define pi acos(-1.0)
#define for(i,a,b) for(int i=(a);i<(b);i++)
#define M 200000+5
map<string,int>mp;
char s[40]; 
int main(){
    int n,i,j;
    while(~scanf("%d",&n)){
mp.clear();
getchar();
while(n--){
gets(s);
if(mp.find(s)==mp.end()){
mp[s]=1;;
puts("OK");
}else{
printf("%s%d\n",s,mp[s]);
mp[s]++;
}
}
}
    return 0;
}