#include<bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
typedef pair<int, int> pii;
constexpr int maxn = 1e5 + 5, maxg = 15;
ll dp[1 << maxg] = { 0 };
ll f[maxn] = { 0 };
ll left_pref[maxn][maxg][maxg] = { 0 }, right_pref[maxn][maxg][maxg] = { 0 };
vector <int> groups[maxg];
int n, g;
// Finding the best way to split the new group given that some groups allready are seated
ll query(int allready, int next_one)
{
int lower = 0, upper = groups[next_one].size(), mid;
ll sleft = 0, sright = 0;
while (lower < upper)
{
mid = (lower + upper) >> 1;
// Testing mid
sleft = sright = 0;
sleft += f[mid] + f[groups[next_one].size() - mid];
sright += f[mid + 1] + f[groups[next_one].size() - mid - 1];
for (int y = 0; y < g; y++)
{
if ((allready & (1 << y)) == 0) continue;
if (groups[next_one][mid] != 0)
sleft += left_pref[groups[next_one][mid] - 1][next_one][y];
sleft += right_pref[groups[next_one][mid]][next_one][y];
if (groups[next_one][mid] + 1 != n)
sright += right_pref[groups[next_one][mid] + 1][next_one][y];
sright += left_pref[groups[next_one][mid]][next_one][y];
}
// cout << mid << " " << sleft << " \t" << mid + 1 << " " << sright << "\n";
if (sleft < sright) upper = mid;
else lower = mid + 1;
}
// cout << allready << " " << next_one << " " << "A" << min(sleft, sright) << "\n";
return min(sleft, sright);
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
for (int i = 1; i < maxn - 1; i++) f[i + 1] = f[i] + i; // Double the actual amount
string s;
cin >> s;
n = s.size();
vector <int> v(n);
for (int i = 0; i < n; i++) {
v[i] = s[i] - 'A';
groups[s[i] - 'A'].emplace_back(i);
g = max(g, s[i] - 'A' + 1);
}
ll sum, seen;
// Making prefixsum from left
for (int x = 0; x < g; x++) // Want to place
{
for (int y = 0; y < g; y++) // Already placed
{
if (x == y) continue;
sum = 0, seen = 0;
for (int i = 0; i < n; i++)
{
if (v[i] == x) sum += seen;
else if (v[i] == y) seen += 2; // Double the actual amount to keep to integers
left_pref[i][x][y] = sum;
// cout << i << " " << seen << " " << sum << "\n";
}
}
}
// Making right prefix
for (int x = 0; x < g; x++) // Want to place
{
for (int y = 0; y < g; y++) // Already placed
{
if (x == y) continue;
sum = 0, seen = 0;
for (int i = n - 1; i >= 0; i--)
{
if (v[i] == x) sum += seen;
else if (v[i] == y) seen += 2; // Double the actual amount to keep to integers
right_pref[i][x][y] = sum;
}
}
}
// Solving with bitset dp
ll best;
for (int i = 0; i < (1 << g); i++)
{
best = 2e15;
for (int y = 0; y < g; y++)
{
if (i & (1 << y))
{
best = min(best, dp[i - (1 << y)] + query(i - (1 << y), y));
// Update best
}
}
if (best == 2e15) best = 0;
dp[i] = best;
}
cout << dp[(1 << g) - 1] / 2;
if (dp[(1 << g) - 1] & 1) cout << ".5";
cout << "\n";
}
