// 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;
const int MAXG = 15;
int n, g;
string s;
int psm[MAXG][MAXN];
ll pre[MAXG + 5][MAXG + 5][MAXN];
ll dp[(1 << MAXG) + 5];
vi vec[MAXG + 5];
inline 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);
}
REP (i, 0, g) {
REP (j, 0, n) {
if (s[j] - 'A' == i) {
cerr << i << ' ' << j << '\n';
vec[i].pb(j);
psm[i][j] = 1;
}
if (j) {
psm[i][j] += psm[i][j - 1];
}
}
}
REP (j, 0, g) {
REP (i, 0, g) {
int all = 0;
REP (k, 0, n) {
if (s[k] - 'A' == i) {
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 (s[k] - 'A' == i) {
acnt++;
}
}
int jc = 0, cnt = 0;
REP (k, 0, n) {
if (s[k] - 'A' == j) {
cur += cnt * 2;
cur -= acnt * 2;
jc++;
} else if (s[k] - 'A' == i) {
cnt++;
acnt--;
}
pre[j][i][k] = cur;
}
}
}
dp[0] = 0;
REP (i, 1, 1 << g) {
dp[i] = LINF;
cerr << bitset<2>(i) << '\n';
REP (j, 0, g) {
if (i >> j & 1 ^ 1) {
continue;
}
cerr << ' ' << j << '\n';
int ni = i ^ (1 << j);
ll mn = LINF;
auto solve = [&] (int k) {
ll tmp = calc(psm[j][k]) + calc(psm[j][n - 1] - psm[j][k]);
REP (l, 0, g) {
if (i >> l & 1 ^ 1) {
continue;
}
tmp += pre[j][l][k];
}
return tmp;
};
if (SZ(vec[j]) == 0) {
mnto(dp[i], dp[ni]);
continue;
}
mnto(dp[i], dp[ni] + solve(0));
int lo = 0, hi = SZ(vec[j]) - 1;
// REP (i, 0, SZ(vec[j])) {
// cerr << " " << i << ' ' << vec[j][i] << ": " << solve(vec[j][i]) << '\n';
// }
while (hi - lo >= 3) {
int mid1 = lo + (hi - lo + 1) / 3, mid2 = mid1 + hi >> 1;
assert(mid1 != mid2);
cerr << " " << lo << ' ' << hi << ' ' << mid1 << ' ' << mid2 << '\n';
ll tmp1 = solve(vec[j][mid1]), tmp2 = solve(vec[j][mid2]);
if (tmp1 <= tmp2) {
hi = mid2;
} else {
lo = mid1;
}
}
REP (k, lo, hi + 1) {
cerr << " " << k << ' ' << vec[j][k] << ": " << solve(vec[j][k]) << '\n';
mnto(dp[i], dp[ni] + solve(vec[j][k]));
}
}
}
ll ans = dp[(1 << g) - 1];
if (ans % 2 == 0) {
ans /= 2;
cout << ans << '\n';
} else {
ans /= 2;
cout << ans << ".5\n";
}
return 0;
}
