731A - Night Museum

using namespace std;
inline int ord(char c) { return c - 'a'; }
int main(void)
{
    int ans = 0, last = 0;
    string s;
    cin >> s;
    for (auto c : s)
    {
        ans += min(26 - abs(ord(c) - last), abs(ord(c) - last));
        last = ord(c);
    }
    cout << ans << endl;
    return 0;
}