#include <bits/stdc++.h>
using namespace std;
#define dd double
#define all(v) v.begin(), v.end()
const int M = 10001, N = 7;
dd e[M],val[N][1<<N][101];
vector<int> a[N];
signed main()
{
ios::sync_with_stdio(0);
cin.tie(NULL), cout.tie(NULL);
for (int 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);
vector<int> v;
for (int i=0;i<N;i++)
v.push_back(i);
for (int i=0;i<N;i++)
for (int m=0;m<(1<<N);m++)
for (int k=0;k<=a[i].size();k++)
{
if (m>>i&1) continue;
for (int j=0;j<N;j++)
{
if ((m>>j)%2==0) continue;
for (int l=0;l<k;l++)
val[i][j][k]+=lower_bound(all(a[j]),a[i][l])-begin(a[j]);
for (int l=k;l<a[i].size();l++)
val[i][j][k]+=a[j].size()-(lower_bound(all(a[j]),a[i][l])-begin(a[j]));
}
}
dd ans=n*(n-1)/2;
do
{
int m=0;
dd vl=0;
for (int i:v)
{
dd mn=n*(n-1)/2;
int sz=a[i].size();
for (int k=0;k<=sz;k++)
mn=min(mn,val[i][m][k]+e[k]+e[sz-k]);
vl+=mn,m+=(1<<i);
}
ans=min(ans,vl);
}while(next_permutation(all(v)));
cout<<ans<<endl;
return 0;
}
