def counts(wrd, q):
    '''统计字频'''
    for x1 in wrd:
        q[x1] += 1
    return q

for line in sys.stdin:
    _, *words, wd, k = line.strip().split(" ")
    a1 = counts(wd, dict.fromkeys(wd, 0))     # 查找词的字频统计
    
    l = []
    for w in words:
        a2 = counts(w, dict.fromkeys(w, 0))   # 被查找词的字频统计
        if wd != w and a1 == a2:               # 符合兄弟词的条件
            l.append(w)

    print(len(l))
    if len(l) >= int(k):
        print(sorted(l)[int(k)-1])