#include <algorithm>
#include <iostream>
#include <vector>
using namespace std;
const int N = 1e5, A = 15;
int p2(const int& i) { return 1 << i; }
long long l[A][N], r[A][N];
vector<int> p[A];
int n;
long long c2(int k) { return 1LL * k * (k - 1) / 2; }
long long cost(int i, int j, int k) {
long long x = c2(k) + c2(p[j].size() - k);
for (int u = 0; u < A; u++)
if (i & p2(u)) {
if (k > 0) x += 2 * l[u][p[j][k - 1]];
if (k < (int)p[j].size()) x += 2 * r[u][p[j][k]];
}
return x;
}
void print(long long x) {
if (x % 2 == 0)
cout << x / 2 << '\n';
else
cout << x / 2 << ".5" << '\n';
}
int main() {
ios::sync_with_stdio(0), cin.tie(0);
string s;
cin >> s;
n = s.size();
for (int i = 0; i < n; i++) p[s[i] - 'A'].push_back(i);
for (int i = 0; i < A; i++) {
static int k[N];
for (int j = 0; j < n; j++)
k[j] = (s[j] - 'A' == i ? 1 : 0) + (j > 0 ? k[j - 1] : 0);
for (int j = 0; j < A; j++) {
int last = -1;
for (int u : p[j])
l[i][u] = k[u] + (last != -1 ? l[i][last] : 0), last = u;
last = -1;
reverse(p[j].begin(), p[j].end());
for (int u : p[j])
r[i][u] = (k[n - 1] - k[u]) + (last != -1 ? r[i][last] : 0), last = u;
reverse(p[j].begin(), p[j].end());
}
}
static long long f[1 << A];
f[0] = 0;
for (int i = 1; i < 1 << A; i++) {
f[i] = 1e18;
for (int j = 0; j < A; j++)
if (i & p2(j)) {
if (p[j].size() == 0) {
f[i] = min(f[i], f[i ^ p2(j)]);
continue;
}
int low = 0, hi = p[j].size();
while (low < hi) {
int m = (low + hi) / 2;
if (cost(i ^ p2(j), j, m) < cost(i ^ p2(j), j, m + 1))
hi = m;
else
low = m + 1;
}
f[i] = min(f[i], f[i ^ p2(j)] + cost(i ^ p2(j), j, low));
}
}
print(f[(1 << A) - 1]);
return 0;
}
