Facebook Hacker Cup 2013 - Qualification - Problem A - Beautiful Strings

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;


   
public class Main {
    public static void main (String[] args) throws IOException {
   
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    StringBuffer sb=new StringBuffer();
    String line;
    while ((line = in.readLine()) != null) {
       String val=line.toLowerCase();
       char[]hist=new char[26];
       for(int i=0;i<val.length();i++){
           if(val.charAt(i)>='a' && val.charAt(i)<='z'){
            hist[val.charAt(i)-'a']++;
           }
       }
       Arrays.sort(hist);
       int sum=0;
       for(int i=hist.length-1;i>-1;i--){
           sum+=hist[i]*(i+1);
       }
       sb.append(sum).append('\n');
    }
    System.out.print(sb);
  }
}