#pragma comment(linker, "/STACK:1024000000,1024000000")#include<cstdio>#include<cstring>#include<cmath>#include<algorithm>#include<vector>#include<map>#include<set>#include<queue>#include<stack>#include<ctime>#include<iostream>using namespace std;typedef long long LL;const double pi=acos(-1.0),eps=1e-10;void File(){    freopen("D:\\in.txt","r",stdin);    freopen("D:\\out.txt","w",stdout);}template <class T>inline void read(T &x){    char c = getchar();    x = 0;    while(!isdigit(c)) c = getchar();    while(isdigit(c))    {        x = x * 10 + c - ‘0‘;        c = getchar();    }}char s[1000];int main(){    cin>>s; int ans=0,len=strlen(s);    ans=ans+min(abs(s[0]-‘a‘),26-abs(s[0]-‘a‘));    for(int i=0;i<len-1;i++)    {        ans=ans+min(abs(s[i]-s[i+1]),26-abs(s[i]-s[i+1]));    }    cout<<ans<<endl;    return 0;}