#include <bits/stdc++.h>
using namespace std;
 
#define S second
#define F first
#define LL long long 
#define LINF 100000000000000000
#define INF 1000000000
 
const int N = 4e5+10;
const LL MOD = 1e9+7;

LL gcd(LL a,LL b){return !b?a:gcd(b,a%b);}

string f(int c,int k){

    string ret = "";
    for(int i=c;i<k;i++)
        ret += i+'a',ret += c+'a';

    return ret;
}

int main()
{      
    //freopen("out.txt","w",stdout);
    string s;
    cin>>s;

    int ans = INF;
    for(int i=0;i<26;i++){
        int ans1 = 0;
        for(char c:s)ans1 += abs(c-'a'-i);
        ans = min(ans,ans1);
    }
    printf("%d\n",ans);
}