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

using namespace std;

int main() {
    // ifstream cin("input.txt");
    // ofstream cout("output.txt");

    string S;
    cin >> S;

    int N;
    cin >> N;

    set<string> Us;

    string u;
    for (int i = 0; i < N; ++i) {
        cin >> u;
        Us.insert(u);
    }

    string T = "";

    int c = 0;
    while (Us.count(S + ((c)?to_string(c):"")  )  ) {
        c++;
    }

    T = S + ((c) ? to_string(c) : "");


    cout << T << endl;

    return 0;
}