#include <cstdio>
#include <iostream>
#include <algorithm>
#include <cstring>
#include <unordered_map>

using namespace std;

string s;

int main(){

    getline(cin,s);
    unordered_map <char,int> times;
    for(int i = 0;i < s.length();i++){
        times[s[i]]++;
    }

    int maxt = 0;
    int mint = 100000000;

    /*
    unordered_map<char,int>::iterator it;
    for(it = times.begin();it != times.end();it++){
        printf("%d",it->second);
    }
    */
    /*
    for(auto t:times){
        printf("%d",t.second);
    }
    */

    for(auto t:times){
        maxt = max(t.second,maxt);
        mint = min(t.second,mint);
    }

    cout << maxt - mint << endl;

    return 0;
}