#include <bits/stdc++.h>
#define file(s) freopen(s".in", "r", stdin); freopen(s".out", "w", stdout);
#define adiyer(); ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define bitcount(n) __builtin_popcountll(n)
#define all(x) x.begin(), x.end()
#define len(s) (int) s.size()
#define md ((l + r) >> 1)
#define pb push_back
#define S second
#define F first
// #define int long long
using namespace std;
typedef long long ll;
typedef long double ld;
const int dx[8] = {1, 0, -1, 0, 1, 1, -1, -1};
const int dy[8] = {0, 1, 0, -1, -1, 1, -1, 1};
const int N = 1e2 + 11;
const int MAX = 1e6;
const int mod = 998244353;
const long long inf = 1e9 + 10;
const double eps = 1e-9;
ll n;
double dp[N];
string s, per;
void output(){
cin >> s;
for(ll i = 0; i < len(s); i++){
if(per.find(s[i]) == -1){
per.pb(s[i]);
}
}
sort(all(per));
double res = inf;
do{
double cur = 0;
bool was[N] = {};
for(char chr : per){
for(ll i = 0; i < len(s); i++){
if(s[i] != chr) continue;
double expf = 0, expb = 0;
for(ll j = 0; j < i; j++){
if(was[j]) expf++;
if(s[j] == chr) expf += 0.5;
}
for(ll j = i + 1; j < len(s); j++){
if(was[j]) expb++;
if(s[j] == chr) expb += 0.5;
}
dp[i] = min(expf, expb);
cur += dp[i];
}
for(ll i = 0; i < len(s); i++)
if(s[i] == chr)
was[i] = 1;
}
res = min(res, cur);
} while(next_permutation(all(per)));
cout << res;
}
const bool cases = 0;
signed main(){
// file("disrupt");
adiyer();
int tt = 1;
if(cases) cin >> tt;
for(int i = 1; i <= tt; i++){
output();
}
}
