#include <iostream>
#include <string>
#include <cmath>

using namespace std;

void maimun()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
}

int minJoystickMoves(string s, string f) {
    int totalMoves = 0;
    int n = s.size();

    for (int i = 0; i < n; i++) {
        int diff = abs(s[i] - f[i]);
        totalMoves += min(diff, 26 - diff);
    }

    return totalMoves;
}

int main() {
    #ifdef ONLINE_JUDGE
        freopen("controller.in","r",stdin);
        freopen("controller.out","w",stdout);
    #endif ONLINE_JUDGE
    maimun();
    string s, f;
    cin>>s>>f;

    cout << minJoystickMoves(s, f) << endl;

    return 0;
}