# -*- coding: utf-8 -*-

def solve(input):
    chain = {}
    s = set([])

    for w in input:
        if w.isdigit() :
            continue

        for i in xrange(len(w)) :
            s.add(w[i])
            if i + 1 < len(w) :
                chain[w[i]] = w[i + 1]

    if len(s) == 1 :
        return s.pop()

    if len(s) - 1 > len(chain) :
        return "-1"

    k = set(chain.keys())
    v = set(chain.values())

    first = ((k ^ v) & k).pop()
    end = ((k ^ v) & v).pop()

    i = first
    r = first

    while i != end :
        r += chain[i]
        i = chain[i]

    return r
    pass

if __name__ == "__main__":
    input = []
    ln = int(raw_input())
    input.append(str(ln))
    for l in xrange(ln):
        input.append(raw_input())

    ln = int(raw_input())
    input.append(str(ln))
    for l in xrange(ln):
        input.append(raw_input())

    print solve(input)