题解 | #字符统计#

import sys

string = input()
alpha = set()
alpha_list = []
table = {}
for i in string:
    alpha.add(i)

for i in alpha:
    alpha_list.append(i)

for i in alpha_list:
    count = 0
    for j in string:
        if i == j:
            count +=1
            table[i] =  count

#先按键排序，再按值排序
sorted_dict = dict(sorted(table.items()))

sorted_dict = dict(sorted(sorted_dict.items(), key=lambda item: item[1],reverse = True),)

keys = sorted_dict.keys()
for i in keys:
    print(i,end = '')