#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);

	map<char, char> pre, nxt;
	int N, sum = 0;

	vector<char> head;
	for(int i = 0; i < 2; i++) {
		cin >> N;
		sum = 0;
		for(int j = 0; j < N; j++) {
			string s;
			cin >> s;
			for(int k = 0; k < s.size() - 1; k++) {
				pre[s[k + 1]] = s[k];
				nxt[s[k]] = s[k + 1];
			}
			head.push_back(s[0]);
			sum += s.size();
		}
	}

	sort(head.begin(), head.end());
	head.erase(unique(head.begin(), head.end()), head.end());

	int s = -1;
	for(int i = 0; i < head.size(); i++) {
		if(pre.count(head[i]) == 0) {
			if(s != -1) {
				cout << -1 << endl;
				return 0;
			}
			s = i;
		}
	}

	string ans;
	char c = head[s];
	while(nxt.count(c)) {
		ans.push_back(c);
		c = nxt[c];
	}
	ans.push_back(c);

	if(sum == ans.size()) {
		cout << ans << endl;
	}
	else {
		cout << -1 << endl;
	}
}