#include <iostream>
#include <fstream>
#include <vector>
#include <list>

using namespace std;


int hashf(int n) {
    int k = n % 10 + ((n / 10) % 10) * 100 + (n / 100) % 10 * 100 + (n / 1000) % 10 * 1000;
    return k;
}

vector <vector <int>> hasht;

int main() {
    ifstream inp("input.txt");
    ofstream outp("output.txt");

    int a;
    while (true) {
        inp >> a;
        if (a == 0) break;
        else if (a > 0) {
            hasht[hashf(a)].push_back(a);
        }
        else {
            for (int i = 0; i < hasht[hashf(-a)].size(); ++i) {
                if (-a == hasht[hashf(-a)][i]) {

                }
            }
        }

    }
    inp.close();
    outp.close();

    return 0;
}