题解 | #数据分类处理#

lst01 = list(map(str, input().split()))[1:]  # 数据
t =  sorted(list(set(map(int,input().split()[1:]))))
lst02 = list((map(str,t)))  # 查询
dict01 = {}
for i in lst02:
    dict01[i] = []
    for j in range(len(lst01)):
        if i in lst01[j]:
            dict01[i].append(j)
            dict01[i].append(lst01[j])
rlst = [0]
for k,v in dict01.items(): # k是key v是列表
    if v == []:
        continue
    rlst.append(k)
    rlst.append(int(len(v)/2))
    for i in v:
        rlst.append(i)
rlst[0] = len(rlst) -1
[print(i,end=' ') for i in rlst]