#include <bits/stdc++.h>
#define iter(a) a.begin(), a.end()
#define lsort(a) sort(iter(a))
#define gsort(a) sort(iter(a), greater<>())
#define eb emplace_back
#define ef emplace_front
#define pob pop_back()
#define pof pop_front()
#define mp make_pair
#define F first
#define S second
#define uni(a) a.resize(unique(iter(a)) - a.begin())
#define printv(a, b) { \
for(auto pv : a) b << pv << " "; \
b << "\n"; \
}
using namespace std;
typedef long long ll;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
template<typename A, typename B>
ostream& operator<<(ostream& o, pair<A, B> p){
return o << '(' << p.F << ',' << p.S << ')';
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
string s;
cin >> s;
int n = s.size();
const int G = 15;
vector<vector<int>> pos(G, vector<int>(1));
vector<int> id(n);
for(int i = 0; i < n; i++){
id[i] = pos[s[i] - 'A'].size();
pos[s[i] - 'A'].eb(i);
}
vector<vector<vector<ll>>> f(G, vector<vector<ll>>(G));
for(int a = 0; a < G; a++){
for(int b = 0; b < G; b++){
f[a][b].resize(pos[a].size() + 1);
ll total = 0;
ll cnt = 0;
for(int i = 0; i < n; i++){
if(s[i] == 'A' + a){
total += cnt;
f[a][b][id[i]] += total;
}
if(s[i] == 'A' + b) cnt++;
}
total = 0;
cnt = 0;
for(int i = n - 1; i >= 0; i--){
if(s[i] == 'A' + a){
f[a][b][id[i]] += total;
total += cnt;
}
if(s[i] == 'A' + b) cnt++;
}
f[a][b][0] = total;
}
}
auto fmsk = [&](int a, int msk, int i){
ll ans = 0;
for(int j = 0; j < G; j++){
if(1 << j & msk) ans += f[a][j][i];
}
return 2 * ans + f[a][a][i];
};
auto best = [&](int a, int msk){
int l = 0, r = pos[a].size(); r--;
while(l < r){
int mid = (l + r) / 2;
if(fmsk(a, msk, mid) >= fmsk(a, msk, mid + 1)) l = mid + 1;
else r = mid;
}
//cerr << "best " << a << " " << bitset<G>(msk) << " : " << l << " " << fmsk(a, msk, l) << "\n";
return l;
};
vector<ll> dp(1 << G, 1LL << 60);
dp[0] = 0;
for(int msk = 0; msk < (1 << G); msk++){
//cerr << "dp " << bitset<G>(msk) << " : " << dp[msk] << "\n";
for(int a = 0; a < G; a++){
if(1 << a & msk) continue;
int nxt = msk | (1 << a);
int b = best(a, msk);
ll t = dp[msk] + fmsk(a, msk, b);
dp[nxt] = min(dp[nxt], t);
//cerr << "trans " << bitset<G>(msk) << " -> " << bitset<G>(nxt) << " " << t << "\n";
}
}
ll ans = dp[(1 << G) - 1];
if(ans % 2 == 0) cout << ans / 2 << "\n";
else cout << ans / 2 << ".5\n";
return 0;
}
