牛客--删除字符串中出现次数最少的字符python

实现删除字符串中出现次数最少的字符，若出现次数最少的字符有多个，则把出现次数最少的字符都删除。输出删除这些单词后的字符串，字符串中其它字符保持原来的顺序。

数据范围：输入的字符串长度满足 1≤n≤20  ，保证输入的字符串中仅出现小写字母

输入：aabcddd

输出：aaddd

import sys

def count_num(s):
    char_count = {}
    for char in s:
        char_count[char] = char_count.get(char, 0) + 1
    return char_count


for line in sys.stdin:
    a = line.split()
    char_count = count_num(a[0])
    min_value = min(char_count.values())
    min_keys = [key for key, value in char_count.items() if value == min_value]
    b = a[0]
    for i in min_keys:
        b = b.replace(i,'')
    print(b)