// Hallelujah, praise the one who set me free
// Hallelujah, death has lost its grip on me
// You have broken every chain, There's salvation in your name
// Jesus Christ, my living hope
#include <bits/stdc++.h>
using namespace std;
#define REP(i, s, e) for (int i = (s); i < (e); i++)
#define RREP(i, s, e) for (int i = (s); i >= (e); i--)
template <class T>
inline bool mnto(T& a, T b) {return a > b ? a = b, 1 : 0;}
template <class T>
inline bool mxto(T& a, T b) {return a < b ? a = b, 1: 0;}
typedef long long ll;
typedef long double ld;
#define FI first
#define SE second
typedef pair<int, int> ii;
typedef pair<ll, ll> pll;
typedef tuple<int, int, int> iii;
#define ALL(_a) _a.begin(), _a.end()
#define SZ(_a) (int) _a.size()
#define pb push_back
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<ii> vii;
typedef vector<iii> viii;
#ifndef DEBUG
#define cerr if (0) cerr
#endif
const int INF = 1000000005;
const ll LINF = 1000000000000000005ll;
const int MAXN = 100005;
int n, g;
string s;
ll dp[MAXN];
ll calc(int n) {
return (ll) n * (n - 1) / 2;
}
int main() {
#ifndef DEBUG
ios::sync_with_stdio(0), cin.tie(0);
#endif
cin >> s;
n = SZ(s);
REP (i, 0, n) {
mxto(g, s[i] - 'A' + 1);
}
dp[0] = 0;
REP (i, 1, 1 << g) {
dp[i] = LINF;
cerr << bitset<5>(i) << '\n';
REP (j, 0, g) {
if (i >> j & 1 ^ 1) {
continue;
}
cerr << ' ' << j << '\n';
int ni = i ^ (1 << j);
int all = 0;
REP (k, 0, n) {
if (ni >> (s[k] - 'A') & 1) {
all++;
}
}
int acnt = 0, ajc = 0;
ll cur = 0;
RREP (k, n - 1, 0) {
if (s[k] - 'A' == j) {
cur += acnt * 2;
ajc++;
} else if (ni >> (s[k] - 'A') & 1) {
acnt++;
}
}
ll mn = cur + calc(ajc);
int jc = 0, cnt = 0;
ll prv = LINF;
bool inc = 0;
REP (k, 0, n) {
if (s[k] - 'A' == j) {
cur += cnt * 2;
cur -= acnt * 2;
jc++;
} else if (ni >> (s[k] - 'A') & 1) {
cnt++;
acnt--;
}
ll tmp = cur + calc(jc) + calc(ajc - jc);
if (tmp > prv) {
inc = 1;
} else if (tmp < prv) {
assert(!inc);
}
cerr << " " << tmp << '\n';
mnto(mn, tmp);
prv = tmp;
}
mnto(dp[i], dp[ni] + mn);
}
}
ll ans = dp[(1 << g) - 1];
if (ans % 2 == 0) {
ans /= 2;
cout << ans << '\n';
} else {
ans /= 2;
cout << ans << ".5\n";
}
return 0;
}
