#include <bits/stdc++.h>
using namespace std;
#define FOR(i, n) for(int i = 0; i < (n); i++)
#define MEM(a, x) memset(a, x, sizeof(a))
#define ALL(a) a.begin(), a.end()
#define UNIQUE(a) a.erase(unique(ALL(a)), a.end())
typedef long long ll;
typedef pair<int, int> P;

int n, m;
char nex[30];

int main(int argc, char const *argv[]) {
	ios_base::sync_with_stdio(false);
	cin >> n;
	fill(nex, nex+30, 'z');
	bool ok = true;
	int cnt = 0;
	FOR(i, n) {
		string s;
		cin >> s;
		cnt += s.size();
		FOR(j, s.size()-1) {
			if (nex[s[j]-'A'] == 'z') nex[s[j]-'A'] = s[j+1];
			else if (nex[s[j]-'A'] != s[j+1]) ok = false;
		}
	}
	cin >> m;
	FOR(i, m) {
		string s;
		cin >> s;
		FOR(j, s.size()-1) {
			if (nex[s[j]-'A'] == 'z') nex[s[j]-'A'] = s[j+1];
			else if (nex[s[j]-'A'] != s[j+1]) ok = false;
		}
	}
	int cnt2 = 0;
	FOR(i, 26) {
		if (nex[i] != 'z') cnt2++;
	}
	if (!ok || cnt != cnt2+1) {
		cout << -1 << endl;
		return 0;
	}
	FOR(i, 26) {
		string ret = "";
		for (char c = (char)('A'+i); c != 'z'; c = nex[c-'A']) {
			ret += string(1, c);
		}
		if (ret.size() == cnt) {
			cout << ret << endl;
			return 0;
		}
	}
	return 0;
}