#include <bits/stdc++.h>
using namespace std;
#ifdef DEBUG
#define dbg(...) printf(__VA_ARGS__);
#define getchar_unlocked getchar
#else
#define dbg(...)
#endif
#define sf scanf
#define pf printf
#define fi first
#define se second
#define pb push_back
#define sz(x) (int)x.size()
#define mnto(x,y) x=min(x,(__typeof__(x))y)
#define mxto(x,y) x=max(x,(__typeof__(x))y)
#define INF 1023456789
#define LINF 1023456789123456789
#define all(x) x.begin(), x.end()
#define disc(x) sort(all(x));x.resize(unique(all(x))-x.begin());
typedef long long ll;
typedef long double ld;
typedef pair<int, int> ii;
typedef pair<ll, ll> pll;
typedef tuple<int, int, int> iii;
typedef tuple<int, int, int, int> iiii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<pll> vll;
mt19937 rng(time(0));
#define mod 1000000007
inline int add(int a,int b){
int r=a+b;
while(r>=mod)r-=mod;
while(r<0)r+=mod;
return r;
}
inline int mult(int a,int b){
return (int)(((ll)(a*b))%mod);
}
inline int rd(){
int x=0;
char ch=getchar_unlocked();
while(!(ch&16))ch=getchar();//keep reading while current character is whitespace
while(ch&16){//this will break when ‘\n’ or ‘ ‘ is encountered
x=(x<<3)+(x<<1)+(ch&15);
ch=getchar_unlocked();
}
return x;
}
#define maxn 100005
#define maxm (1<<15)
void print2(ll x){
if(x%2)pf("%lld.5\n",x/2);
else pf("%lld\n",x/2);
}
int n,a[maxn],num[15],pos[15][maxn];
ll pfx[15][15][maxn],sfx[15][15][maxn];
ll memo[maxm+5],memo2[maxm+5][15];
char str[maxn];
ll cost(int mask,int x,int y){
int p=pos[x][y],p2=pos[x][y+1];
ll ans=0;
for(int i=0;i<15;++i){
if((mask&(1<<i))!=0)ans+=pfx[i][x][p]+sfx[i][x][p2];
}
ll b=y,a=num[x]-y;
ans*=2;
ans+=(b*(b-1)+a*(a-1))/2;
return ans;
}
ll calc(int mask,int x){
if(num[x]==0)return 0;
if(memo2[mask][x]!=-1)return memo2[mask][x];
int lo=0,hi=num[x];
while(hi-lo>=3){
int m1=lo+(hi-lo+1)/3,m2=m1+hi>>1;
if(cost(mask,x,m1)<=cost(mask,x,m2))hi=m2;
else lo=m1;
}
ll ans=LINF;
for(int i=lo;i<=hi;++i){
ans=min(ans,cost(mask,x,i));
}
return memo2[mask][x]=ans;
}
ll dp(int mask){
if(mask==maxm-1)return 0;
if(memo[mask]!=-1)return memo[mask];
ll mn=LINF;int best=0;
for(int i=0;i<15;++i){
if((mask&(1<<i))!=0)continue;
int nmask=mask^(1<<i);
ll tmp=calc(mask,i)+dp(nmask);
if(tmp<=mn){
mn=tmp;best=i;
}
}
return memo[mask]=mn;
}
int main(){
sf(" %s",&str);
n=strlen(str);
for(int i=1;i<=n;++i){
a[i]=str[i-1]-'A';
++num[a[i]];
pos[a[i]][num[a[i]]]=i;
pos[a[i]][num[a[i]]+1]=n+1;
}
for(int i=0;i<maxm;++i){
memo[i]=-1;
for(int j=0;j<15;++j){
memo2[i][j]=-1;
}
}
for(int x=0;x<15;++x){
for(int y=0;y<15;++y){
int cnt=0;
for(int i=1;i<=n;++i){
pfx[x][y][i]=pfx[x][y][i-1];
if(a[i]==x)++cnt;
if(a[i]==y)pfx[x][y][i]+=cnt;
}
cnt=0;
for(int i=n;i>=1;--i){
sfx[x][y][i]=sfx[x][y][i+1];
if(a[i]==x)++cnt;
if(a[i]==y)sfx[x][y][i]+=cnt;
}
}
}
print2(dp(0));
}
