#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
#else
  #define Debug(...) void(0)
#endif
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  string s;
  cin >> s;
  int n = s.size();
  int ans = 0;
  for (int i = 0; i < n; ++i) {
    for (int j = n - 1; j > i; --j) {
      if (s[j] < s[j - 1]) {
        swap(s[j], s[j - 1]);
        ++ans;
      }
    }
  }
  cout << ans << endl;
  return 0;
}