set4

#include <iostream>
#include <cmath>
#include <vector>
#include <algorithm>
#include <string>
#include <fstream>
#include <sstream>
#include <set>

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

int main() {
    set <int> chet;
    set <int> nechet;
    string s;
    int f = 0;
    int k;
    while (getline(in, s)) {
        stringstream sin(s);
        while (sin >> k) {
            if (f % 2 == 0) {
                chet.insert(k);
            }
            else {
                nechet.insert(k);
            }
        }
        f++;
    }

    for (auto it : nechet) {
        chet.erase(it);
    }

    for (auto it : chet) {
        out << it << " ";
    }
}


455  455
455
2121
0
666 33 288
3100
555
555 555