import java.util.*;

public class Main{
    static HashMap<Character,Integer> map = new HashMap<Character,Integer>();
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        String x = sc.nextLine();
        for(int i = 0; i<x.length(); i++){
            map.put(x.charAt(i),map.getOrDefault(x.charAt(i),0)+1);
        }
        int max = Integer.MIN_VALUE,min = Integer.MAX_VALUE;
        for(Map.Entry<Character,Integer> set:map.entrySet()){
            int value = set.getValue();
            if(max < value) max = value;
            if(min > value) min = value;
        }
        System.out.println(max - min);
    }
}