#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
int main()
{
   char ch, input[100], output[100];
   int no[26] = {0}, n, c, t, x;
 
   printf("Enter some text\n");
   scanf("%s", input);
 
   n = strlen(input);
 
   /** Store how many times characters (a to z) 
      appears in input string in array */
 
   for (c = 0; c < n; c++)
   {
      ch = input[c] - 'a';
      no[ch]++;
   }
 
   t = 0;
 
   /** Insert characters a to z in output string 
       that many number of times as they appear 
       in input string */
 
   for (ch = 'a'; ch <= 'z'; ch++)
   {
      x = ch - 'a';
 
      for (c = 0; c < no[x]; c++)
      {
         output[t] = ch;
         t++;
      }
   }
   output[t] = '\0';
 
   printf("%s\n", output);
 
   return 0;
}