题解 | #数据分类处理#

lis_I = list(map(int,input().strip().split()))[1:]
lis_R = list(map(int,input().strip().split()))[1:]

new_R = []
check_lis = []
final_lis = []

for char in lis_R:
    if char not in new_R:
        new_R.append(char)

for i in range(len(new_R)):
    for j in range(i,len(new_R)):
        mid = 0
        if new_R[i] > new_R[j]:
            mid = new_R[j]
            new_R[j] = new_R[i]
            new_R[i] = mid

new_R = list(map(lambda x : str(x),new_R))
lis_I = list(map(lambda x : str(x),lis_I))

for char in new_R:
    check_num = 0
    for i in range(len(lis_I)):
        if char in lis_I[i]:
            add_ele = str(i)+' '+str(lis_I[i])
            final_lis.append(add_ele)
            check_num +=1
    if char not in check_lis and check_num > 0:
        add_ele1 = char + ' ' + str(check_num)
        check_lis.append(char)
        final_lis.insert(len(final_lis)-check_num,add_ele1)
        
num_count = len(final_lis)*2

print(num_count,*final_lis,sep=' ')      #*my_list 用于将列表的元素展开为单独的参数。

十分粗糙的解法