编写一个程序，接收用户输入的一个字符串(可以包含空格)，统计其中所有出现过的所有字符，并按照频率高低的顺序排列输出。频率相同的字符按输入顺序输出。-Write a program that receives user input a string (may contain spaces), all of which appeared in the statistics of all characters, and in accordance with the order of frequency