Arrange Alphabets - Descending Order - Java,Python,C

A string S (with only LOWER case alphabets and length from 3 to 100) will be passed  as input. The program should print the alphabets in the string in descending order.

Input Format:
The first line will contain S.

Output Format:
The first line will contain the alphabets present in S in descending order.

Example Input/Output 1:
Input:
cake

Output:
keca

Example Input/Output 2:
Input:
innovation

Output:
vtonia

Source Code:  //Java

import java.util.*;

public class Hello {

public static void main(String[] args) {

Scanner sc=new Scanner(System.in);

String s=sc.next();

char[] c=s.toCharArray();

TreeSet<Character> h=new TreeSet<Character>();

Iterator it;

for(int i=0;i<c.length;i++)

h.add(c[i]);

it=h.descendingIterator();

while(it.hasNext())

{

    System.out.print(it.next());

}

    }

}

Source Code: //C

#include<stdio.h>

#include <stdlib.h>

#include<string.h>

int main()

{

char s[100],t,b[100];

scanf("%s",s);

int i,j,k=0,c=0;

for(i=0;i<strlen(s);i++)

{

    for(j=0;j<i;j++)

    {

        if(s[i]==s[j])

            c=1;

    }

    if(c==0)

        b[k++]=s[i];

    c=0;

}

for(i=0;i<strlen(b)-1;i++)

{

    for(j=i+1;j<strlen(b);j++)

    {

        if(b[i]>b[j])

        {

            t=b[i];

            b[i]=b[j];

            b[j]=t;

        }

    }

}

for(i=strlen(b)-1;i>=0;i--)

printf("%c",b[i]);

}

Source Code: //Python

import itertools

print(''.join(i for i,j in itertools.groupby(sorted(input(),reverse=True))))

Aliter:(Method 2)

n=input()

print(''.join(sorted(set(n)))[::-1])