j задача set/map

#include <iostream>
#include <fstream>
#include <iomanip>
#include <string>
#include <algorithm>
#include <set>
#include <list>
#include <sstream>
#include <vector>
#include <map>
#include <stdlib.h>

using namespace std;
ifstream in("input.txt");
ofstream out("output.txt");

int main() {
    map <string, string> m;
    string x, y;
    int n; cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> x;
        if (m.find(x)  == m.end()) {
            m[x] = "OK";
        }
        else {
            y = x + to_string(m.count(x));
            auto it = m.end();
            m[y] = x + to_string(m.count(x));
        }
    }

    for (auto x : m) {
        cout << x.first << endl;
    }
}