#include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) begin(v),end(v)
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }
using ll = long long;
using pii = pair<int, int>;
constexpr ll INF = 1ll<<30;
constexpr ll longINF = 1ll<<60;
constexpr ll MOD = 1000000007;
constexpr bool debug = false;
//---------------------------------//

int main() {
	int N, M;
	vector<string> S;
	cin >> N;
	REP(i, N) { string s; cin >> s; S.emplace_back(s); }
	cin >> M;
	REP(i, M) { string s; cin >> s; S.emplace_back(s); }
	
	vector<int> nex(26, -1), indeg(26), exist(26);
	REP(i, N + M) for (char c : S[i]) exist[c - 'A'] = true;
	REP(i, N + M) FOR(j, 1, S[i].size()) {
		const char u = S[i][j - 1] - 'A';
		const char v = S[i][j] - 'A';
		if (nex[u] != -1) continue;
		nex[u] = v;
		++indeg[v];
	}
	int c = -1;
	REP(i, 26) {
		if (exist[i] && indeg[i] == 0) {
			if (c != -1) { puts("-1"); return 0; }
			c = i;
		}
	}
	for (; c != -1; c = nex[c]) putchar(c + 'A');
	puts("");
}