#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=int(a);i<int(b);++i)
using namespace std;
typedef long long ll;
int INF = (1LL << 30) - 1;
int MOD = 1e9+7;
string cat(string s,string t){
    if(s.find(t) != -1)return s;
    if(t.find(s) != -1)return t;
    rep(i,0,s.size()){
        if(s[i] == t[0]){
            return s.substr(0,i) + t;
        }
    }
    rep(i,0,t.size()){
        if(s[0] == t[i]){
            return t.substr(0,i) + s;
        }
    }
    return "";
}
main(){
    int N,M;
    set<string> st;
    cin >> N;
    rep(i,0,N){
        string s;
        cin >> s;
        st.insert(s);
    }
    cin >> M;
    rep(i,0,M){
        string s;
        cin >> s;
        st.insert(s);
    }
    bool flag = 1;
    while(st.size() != 1 && flag){
        flag = 0;
        next:
        for(auto S = st.begin();S != st.end();S++)
        for(auto T = st.begin();T != st.end();T++){
            //cout << *S << " " << *T << endl;
            if(S == T)continue;
            string str = cat(*S,*T);
            //cout << "str:" << str << endl;
            if(str != ""){
                flag = 1;
                st.erase(S);
                st.erase(T);                
                st.insert(str);
                //cout << "hogeee" << endl;
                goto next;
            }
        }
        //cout << st.size() << endl;
    }
    if(st.size() == 1)cout << *st.begin() << endl;
    else              cout << -1 << endl;
}