#include<bits/stdc++.h>
using namespace std;

long long n;

void fastIO()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
}

int main ()
{
    freopen("controller.in", "r", stdin);
    freopen("controller.out", "w", stdout);


    fastIO();

    string a, b;
    cin>>a>>b;
    long long ans=0;
    for (long long i=0; i<a.size(); i++)
    {
        if (a[i]<=b[i])
        {
            ans+=min(b[i]-a[i], a[i]-'a'+1+'z'-b[i]);
        }
        else
        {
            ans+=min(a[i]-b[i], b[i]-'a'+1+'z'-a[i]);
        }
    }
    cout<<ans<<endl;
    return 0;
}