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


 using namespace std;


 #define for_n for(int i=0;i!=n; ++i)


 int main()
 {
     vector <string> v;
     string s;
     cin>>s;
     int n; cin>>n;
     for_n {string t; cin>>t; v.push_back(t);}
     sort(v.begin(), v.end());
     for_n if (s==v[i].substr(0,s.length())){cout<<v[i];return 0;} else {cout<<s; break;}
 }