#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int main(){
cin.tie(0)->sync_with_stdio(0);
const int G = 15;
vector<int> seat[G];
vector<ll> cross[G][G]; // [j][g] = j crosses g
{ // total crosses needed
string s;
cin >> s;
int n = s.size();
for(int i=0; i<n; i++) seat[s[i]-'A'].push_back(i+1);
vector<int> pre(n+1);
for(int g=0; g<G; g++){
pre[0] = 0;
for(int i=0; i<n; i++)
pre[i+1] = pre[i]+(s[i]=='A'+g);
for(int j=0; j<G; j++){
auto &v = cross[j][g];
v = {0};
for(const int i : seat[j]) v.push_back(v.back()+pre[i]);
}
pre[n] = 0;
for(int i=n-1; ~i; i--) pre[i] = pre[i+1]+(s[i]=='A'+g);
for(int j=0; j<G; j++){
auto &v = cross[j][g];
ll suf = 0;
for(int i=(int)seat[j].size()-1; ~i; i--)
v[i] += (suf += pre[seat[j][i]-1]);
}
for(int j=0; j<G; j++){
if(j==g){
for(auto &c: cross[j][g]) c -= seat[j].size();
}
else{
for(auto &c: cross[j][g]) c <<= 1;
}
}
}
}
ll dp[1<<G];
memset(dp, 0x3f, sizeof(dp));
auto E = [&](int mask, int g)->ll{
auto cost = [&](int i)->ll{
ll ans = 0;
for(int j=0; j<G; j++){
if((mask>>j)&1) ans += cross[g][j][i];
}
return ans;
};
int l = 0, r = seat[g].size();
while(l<r){
int mid = (l+r)>>1;
if(cost(mid+1)>cost(mid)) r = mid;
else l = mid+1;
}
return cost(l);
};
dp[0] = 0;
for(int mask = 1; mask<(1<<G); mask++){
for(int g=0; g<G; g++){
if((mask>>g)&1) dp[mask] = min(dp[mask], dp[mask^(1<<g)]+E(mask, g));
}
}
ll ans = dp[(1<<G)-1];
if(ans&1) cout << (ans>>1) << ".5\n";
else cout << (ans>>1) << '\n';
}
