#define F first
#define S second
#define rep(i,a,b) for(int i=a;!(a==b&&i!=b)&&((i<=b&&b>=a)||(i>=b&&a>=b));i+=(a<=b?1:-1))
#define pb push_back
#define Fbitl __builtin_ffs
#define bit1 __builtin_popcount
#include <iostream>
#include <math.h>
#include <algorithm>
#include <string.h>
#include <vector>
#include <queue>
#include <map>
#include <unordered_map>

using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<string, string> pss;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pii> vii;
typedef vector<ll> vl;
typedef vector<vl> vvl;
int ma[200];
int main(){
   ios_base::sync_with_stdio(0);cin.tie(0);
   string s;
   cin >> s;
   rep (i,0,s.length()-1) {
       rep(j,'a','z') {
           ma[j] += abs(s[i]-j);
       }
   }
   int mn = 1e9 ;
   rep(i,'a','z'){
       mn = min(mn,ma[i]);
   }
   cout << mn;
   return 0;
}