题解 | #字符统计#

import java.util.*;
import java.io.*;

public class Main{
    public static void main(String [] args) throws Exception{
        BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
        char [] arr = bf.readLine().toCharArray();
        int [] num = new int[123];
        for(char x : arr){
            num[x]++;
        }
        int [] temp = Arrays.copyOf(num,num.length);
        Arrays.sort(temp);
        StringBuilder sb = new StringBuilder();
        for(int i = temp.length-1; i>=0;i--){
            if(temp[i] == 0){
                break;
            }
            if(i<temp.length-1 && temp[i] == temp[i+1]){
                continue;
            }
            for(int j =48;  j<123; j++){
                if(temp[i] == num[j]){
                    sb.append((char)j);
                }
            }  
        }
        System.out.println(sb.toString());

    }
}