#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll, int> pii;
const int N = 1e5+100;
const ll INF = 1e18;
const int G = 15;
vector<int> idx[N];
ll n, cross[G][G][N];
string s;
ll dist[1<<G];
ll nc2(ll x) {
if (x < 2) return 0;
return x*(x-1)/2;
}
ll calc(int msk, int u, int k) {
ll res=0;
for (int i=0; i<G; ++i) {
if (!(msk&(1<<i))) continue;
res+=2*cross[u][i][k];
} int sz=idx[u].size();
res+=nc2(k)+nc2(sz-k);
return res;
}
// cost to go MSK -> MSK^u
ll cost(int msk, int u) {
ll sz=idx[u].size();
int l=0, r=sz-1, res=0;
while (l <= r) {
int m=(l+r)/2;
if (calc(msk, u, m) > calc(msk, u, m+1)) res=m+1, l=m+1;
else r=m-1;
} return min(calc(msk, u, 0), calc(msk, u, res));
}
void solve() {
cin>>s;
n=s.size();
for (int i=0; i<n; ++i) idx[s[i]-'A'].push_back(i+1);
for (int a=0; a<G; ++a) {
for (int b=0; b<G; ++b) {
if (a == b) continue;
ll ps[n+1]={};
for (auto u : idx[b]) ++ps[u];
for (int i=1; i<=n; ++i) ps[i]+=ps[i-1];
int sz=idx[a].size();
ll psum=0, ssum=0;
for (auto x : idx[a]) ssum+=(ps[n]-ps[x-1]);
cross[a][b][0]=ssum;
for (int i=1; i<=sz; ++i) {
int x=idx[a][i-1];
psum+=ps[x], ssum-=(ps[n]-ps[x-1]);
cross[a][b][i]=psum+ssum;
}
}
}
for (int i=0; i<(1<<G); ++i) dist[i]=INF;
dist[0]=0;
priority_queue<pii, vector<pii>, greater<pii>> pq;
pq.push({0, 0});
while (!pq.empty()) {
pii x=pq.top(); pq.pop();
ll d=x.first;
int msk=x.second;
if (dist[msk] < d) continue;
for (int i=0; i<G; ++i) {
if (msk&(1<<i)) continue;
if (dist[msk^(1<<i)] > dist[msk]+cost(msk, i)) {
dist[msk^(1<<i)]=dist[msk]+cost(msk, i);
pq.push({dist[msk^(1<<i)], msk^(1<<i)});
}
}
} assert(dist[(1<<G)-1] < INF);
cout<<dist[(1<<G)-1]/2;
if (dist[(1<<G)-1]%2) cout<<".5\n";
else cout<<"\n";
}
int main() {
int t=1; //cin>>t;
while (t--) solve();
}
