#include <bits/stdc++.h>
#define gibon ios::sync_with_stdio(false); cin.tie(0);
#define fir first
#define sec second
#define pdd pair<long double, long double>
#define pii pair<int, int>
#define pll pair<ll, ll>
#define ld long double
#define pmax pair<__int128, __int128>
#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
typedef long long ll;
typedef unsigned int uint;
using namespace std;
int dx[4]= {0, 1, 0, -1}, dy[4]= {1, 0, -1, 0};
int ddx[8]={1, 1, 0, -1, -1, -1, 0, 1}, ddy[8]={0, 1, 1, 1, 0, -1, -1, -1};
const int mxN=100010;
const int mxM=35000;
const int mxK=1000000000;
const int MOD=1e9+7;
const ll INF=2e18;
int N;
char S[mxN];
int pref[mxN][15];
ll cost[mxN][16][16];
vector <int> apos[16];
bool alph[mxN][16];
ll dp[mxM];
bool Chk[mxM];
ll sum(int s, int e, int idx)
{
return pref[e][idx]-pref[s-1][idx];
}
ll calc(int now, ll pos, vector <int> &comp)
{
ll val=0, nowpos=(pos==0 ? 0 : apos[now][pos-1]);
for(int nxt : comp) if(nxt!=now)
{
val+=cost[nowpos][now][nxt];
}
ll siz=apos[now].size();
val+=pos*(pos-1)/2+(siz-pos)*(siz-pos-1)/2;
return val;
}
void dping(int idx)
{
//printf("idx=%d\n", idx);
vector <int> comp;
for(int i=0;i<15;i++) if((1<<i)&idx)
{
comp.push_back(i);
if(!Chk[idx-(1<<i)]) dping(idx-(1<<i));
}
for(int ele : comp) if(apos[ele].empty())
{
dp[idx]=dp[idx-(1<<ele)];
Chk[idx]=true;
return;
}
dp[idx]=INF;
for(int now : comp)
{
int s=0, e=apos[now].size();
while(s<=e-3)
{
int mid1=(s+e)/2, mid2=(s+e)/2+1;
if(calc(now, mid1, comp)<calc(now, mid2, comp)) e=mid2;
else s=mid1;
}
for(int i=s;i<=e;i++)
{
dp[idx]=min(dp[idx], dp[idx-(1<<now)]+calc(now, i, comp));
}
}
Chk[idx]=true;
}
int main()
{
gibon
cin >> S+1;
N=strlen(S+1);
for(int i=0;i<15;i++)
{
for(int j=1;j<=N;j++) if(S[j]==i+'A')
{
alph[j][i]=1;
apos[i].push_back(j);
}
}
for(int i=0;i<15;i++) for(int j=1;j<=N;j++) pref[j][i]=pref[j-1][i]+alph[j][i];
for(int i=0;i<15;i++)
{
for(int j=0;j<15;j++) if(i!=j && apos[i].size() && apos[j].size())
{
for(int ele : apos[i]) cost[0][i][j]+=2*sum(ele, N, j);
int siz=apos[i].size();
for(int k=0;k<apos[i].size();k++)
{
int now=apos[i][k], pre=(k==0 ? 0 : apos[i][k-1]);
cost[now][i][j]=cost[pre][i][j]-2*sum(now, N, j)+2*sum(1, now, j);
//printf("cost[%d][%d][%d]=%lld\n", now, i, j, cost[now][i][j]);
}
}
}
Chk[0]=true;
for(int i=0;i<15;i++) Chk[1<<i]=true;
for(int i=0;i<15;i++)
{
ll nsiz=apos[i].size(), mid=nsiz/2;
dp[1<<i]=mid*(mid-1)/2+(nsiz-mid)*(nsiz-mid-1)/2;
}
dping((1<<15)-1);
if(dp[(1<<15)-1]%2==0) cout << dp[(1<<15)-1]/2;
else cout << dp[(1<<15)-1]/2 << ".5";
}
