#include <iostream>
#include <fstream>
#include <string>
#include <vector>
#include <algorithm>
#include <string>

using namespace std;

const int LENGTH = 1000;

void readData(string *words)
{
    string tmp;
    ifstream file;
    file.open("NAPIS.TXT");

    for (int i = 0; i < LENGTH; i++) {
        file >> words[i];
    }

    file.close();
}

void findAllRepeatingWords(string *words)
{
    string repeated;

    int i = 0;
    while (i < LENGTH) {
        repeated = "";
        while (words[i++].compare(words[i]) == 0) {
            repeated = words[i];
        }
        if (!repeated.empty()) {
            cout << repeated << endl;
        }
    }
}

int main()
{
    string words[LENGTH];
    readData(words);
    sort(words, words + LENGTH);
    findAllRepeatingWords(words);

    return 0;
}