#include "bits/stdc++.h"
using namespace std;
#define int long long
#define FOR(i, a, b) for(int i=(a);i<(b);i++)
#define RFOR(i, a, b) for(int i=(b-1);i>=(a);i--)
#define REP(i, n) for(int i=0; i<(n); i++)
#define RREP(i, n) for(int i=(n-1); i>=0; i--)
#define ALL(a) (a).begin(),(a).end()
#define UNIQUE_SORT(l) sort(ALL(l)); l.erase(unique(ALL(l)), l.end());
#define CONTAIN(a, b) find(ALL(a), (b)) != (a).end()
#define array2(type, x, y) array<array<type, y>, x>
#define vector2(type) vector<vector<type> >
#define out(...) printf(__VA_ARGS__)

typedef pair<int, int> pos;
int pos::*x = &pos::first;
int pos::*y = &pos::second;

int dxy[] = {0, 1, 0, -1, 0};

/*================================*/

int N, M;
string master;
vector<string> words;

bool merge() {
    REP(i, words.size()) {
        string word = words[i];
        REP(mi, master.length()) {
            char m = master[mi];
            REP(wi, word.length()) {
                char w = word[wi];
                if (m == w) {
                    // masterに結合
                    if (master.length() - mi < word.length() - wi) {
                        master = master.substr(0, mi) + word.substr(wi);
                    }
                    if (mi < wi) {
                        master = word.substr(0, wi) + master.substr(mi);
                    }
                    words.erase(words.begin() + i);
                    return true;
                }
            }
        }
    }
    return false;
}

signed main()
{
#if DEBUG
    std::ifstream in("input.txt");
    std::cin.rdbuf(in.rdbuf());
#endif
    string s;
    cin >> N;
    REP(i, N) {
        cin >> s;
        words.push_back(s);
    }
    cin >> M;
    REP(i, M) {
        cin >> s;
        words.push_back(s);
    }
    
    master = words.back();
    words.pop_back();
    
    while (merge()) {}
    
    if (words.empty()) {
        cout << master << endl;
    } else {
        cout << -1 << endl;
    }
    
    return 0;
}