#include "bits/stdc++.h"

#define REP(i,n) for(ll i=0;i<n;++i)
#define RREP(i,n) for(ll i=n-1;i>=0;--i)
#define FOR(i,m,n) for(ll i=m;i<n;++i)
#define RFOR(i,m,n) for(ll i=n-1;i>=m;--i)
#define ALL(v) (v).begin(),(v).end()
#define PB(a) push_back(a)
#define UNIQUE(v) v.erase(unique(ALL(v)),v.end());
#define DUMP(v) REP(aa, (v).size()) { cout << v[a]; if (a != v.size() - 1)cout << " "; else cout << endl; }
#define INF 1000000001ll
#define MOD 1000000007ll
#define EPS 1e-9

const int dx[8] = { 1,1,0,-1,-1,-1,0,1 };
const int dy[8] = { 0,1,1,1,0,-1,-1,-1 };


using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<vi> vvi;
typedef vector<vl> vvl;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
ll max(ll a, int b) { return max(a, ll(b)); }
ll max(int a, ll b) { return max(ll(a), b); }
ll min(ll a, int b) { return min(a, ll(b)); }
ll min(int a, ll b) { return min(ll(a), b); }
///(´・ω・`)(´・ω・`)(´・ω・`)(´・ω・`)(´・ω・`)(´・ω・`)///
int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	vvi g(26);
	int n, m;
	cin >> n;
	vector<string> v(n);
	REP(i, n)cin >> v[i];
	cin >> m;
	vector<string> w(m);
	REP(i, m)cin >> w[i];
	REP(i, n) {
		REP(j, v[i].size()-1) {
			if(g[v[i][j] - 'A'].size() == 0)g[v[i][j] - 'A'].push_back(v[i][j + 1] - 'A');
		}
	}
	REP(i, m) {
		REP(j, w[i].size()-1) {
			if(g[w[i][j]-'A'].size()==0)g[w[i][j] - 'A'].push_back(w[i][j + 1] - 'A');
		}
	}
	int cnt = 0;
	vi found(26, 0);
	REP(i, n)REP(j, v[i].size())found[v[i][j] - 'A']++;
	REP(i, n)cnt += v[i].size();
	REP(i, 26) {
		assert(g[i].size() <= 1);
		if (found[i]) {
			int p = i; string s;
			while (g[p].size()) {
				s += 'A' + p;
				p = g[p][0];
			}
			s += p + 'A';
			if (s.size() == cnt) {
				cout << s << endl;
				return 0;
			}
			
		}
	}
	cout << -1 << endl;
	return 0;
}