#include <iostream>
#include <vector>
#include <string>
#include <queue>
#include <set>
using namespace std;

int main(){
    int n;
    cin >> n;
    vector<string> a(n);
    for(auto &p: a) cin >> p;
    int m;
    cin >> m;
    vector<string> b(m);
    for(auto &p: b) cin >> p;

    vector<set<int>> G(26);
    vector<int> is_exist(26);
    int len = 0;
    for(auto &p: a){
        len += p.length();
        for(auto &pp: p) is_exist[pp-'A'] = 1;
        for(int i = 1; i < p.length(); i++){
            G[p[i-1]-'A'].insert(p[i]-'A');
        }
    }
    for(auto &p: b){
        for(int i = 1; i < p.length(); i++){
            G[p[i-1]-'A'].insert(p[i]-'A');
        }
    }

    vector<int> in(26);
    for(int i = 0; i < 26; i++){
        for(auto &p: G[i]){
            in[p]++;
        }
    }

    vector<int> ans;
    queue<int> Q;
    for(int i = 0; i < 26; i++){
        if(is_exist[i] && in[i] == 0) Q.push(i);
    }

    if(Q.size() != 1){
        cout << -1 << endl;
        return 0;
    }

    while(Q.size()){
        int c = Q.front(); Q.pop();
        ans.push_back(c);
        for(auto &p: G[c]){
            in[p]--;
            if(in[p] == 0){
                Q.push(p);
            }
        }
    }
    /*
    for(int i = 0; i < 26; i++){
        cout << is_exist[i] << " : " << in[i] << " : " << G[i].size() << ": ";
        for(auto &p: G[i]) cout << p << " ";
        cout << endl;
    }
    for(auto &p: ans) cout << p << " ";
    */
    if(ans.size() != len) cout << -1 << endl;
    else{
        string st = "";
        for(auto &p: ans) st += (char)(p+'A');
        cout << st << endl;
    }
    return 0;
}