#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <map>
#include <set>
#include <iomanip>
#include <cmath>
#include <cassert>
using namespace std;

#define all(x) x.begin(), x.end()
#define pb push_back
#define sz(a) ((int) a.size())

using ll = long long;
const int mod = 1e9 + 7;
ll fast_power(ll base, ll power)
{
    ll ans = 1;
    while (power > 0){
        if (power & 1) ans = (ans*base) % mod;
        base = (base*base) % mod;
        power >>= 1;
    }
    return ans;
}
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed;
    cout.precision(6);
    string s;
    cin >> s;
    sort(s.begin(), s.end());
    int cnt = 0;
    for (int i = 0; i < s.size(); i++) {
        cnt += abs(s[i] - s[s.size() / 2]);
    }
    cout << cnt;



    return 0;
}