#include <bits/stdc++.h>
using namespace std;
#define dd double
#define all(v) v.begin(), v.end()
const int M = 100001, N = 10, M1 = 10000;
dd e[M],pre[1<<N][M],dp[1<<N];
vector<int> a[N];
signed main()
{
ios::sync_with_stdio(0);
cin.tie(NULL), cout.tie(NULL);
cout<<fixed<<setprecision(10);
for (long long i=2;i<M;i++)
e[i]=i*(i-1)/4.0;
string s;
cin>>s;
int n=s.size();
for (int i=0;i<n;i++)
a[s[i]-'A'].push_back(i);
if (a[0].size()==n)
{
cout<<e[n/2]+e[n-n/2]<<endl;
return 0;
}
vector<int> v;
for (int i=0;i<N;i++)
{
v.push_back(i);
for (int j:a[i])
pre[(1<<i)][j]++;
for (int j=1;j<M1;j++)
pre[(1<<i)][j]+=pre[(1<<i)][j-1];
}
for (int m=1;m<(1<<N);m++)
{
if (__builtin_popcount(m)<2) continue;
int p=m&-m;
for (int i=0;i<M1;i++)
pre[m][i]=pre[p][i]+pre[m^p][i];
}
int fin=0;
for (int m=1;m<(1<<N);m++)
{
if (__builtin_popcount(m)==1)
{
int p=31-__builtin_clz(m),sz=a[p].size();
if (sz) fin+=m;
dp[m]=e[sz/2]+e[sz-sz/2];
continue;
}
dp[m]=n*(n-1)/2;
for (int p=0;p<N;p++)
{
if ((m>>p)%2==0) continue;
int m1=m^(1<<p),sz=a[p].size();
if (!sz) continue;
dd val[sz],val1[sz];
for (int i=0;i<sz;i++)
val[i]=pre[m1][a[p][i]],val1[i]=pre[m1][M1-1]-pre[m1][a[p][i]];
for (int i=1;i<sz;i++) val[i]+=val[i-1];
for (int i=sz-2;i>=0;i--) val1[i]+=val1[i+1];
dp[m]=min(dp[m],min(val[sz-1],val1[0])+e[sz]+dp[m1]);
for (int i=1;i<sz;i++)
dp[m]=min(dp[m],dp[m1]+val[i-1]+val1[i]+e[i]+e[sz-i]);
}
}
cout<<dp[fin]<<endl;
return 0;
}
