#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    string s;
    cin >> s;

    int ans = 0;
    for (int i = 0; i < s.size() - 1; i++) {
        for (int j = s.size() - 1; j > i; j--) {
            if (s[j] < s[j - 1]) {
                char tmp = s[j];
                s[j] = s[j - 1];
                s[j - 1] = tmp;
                ans++;
            }
        }
    }

    cout << ans << endl;

    return 0;
}