def run(I,R):
    R = list(map(int,R))
    R = sorted(list(set(R)))
    R = list(map(str,R))
    tmp = [[] for _ in range(len(R))]
    for _ii, i in enumerate(I):
        for _ri,r in enumerate(R):
            if r in i:
                tmp[_ri].append(_ii)
    res = []
    for i,t in enumerate(tmp):
        if len(t) > 0:
            res.append(R[i])
            res.append(str(len(t)))
            for _t in t:
                res.append(str(_t))
                res.append(I[_t])
    res = [str(len(res))]+res
    return " ".join(res)

I = input().split()[1:]
R = input().split()[1:]
print(run(I,R))