#include <bits/stdc++.h>
using namespace std;
int main() {
    // Reading input
    freopen("controller.in", "r", stdin);
    freopen("controller.out", "w", stdout);
    string s, f;
    cin >> s;
    cin >> f;
    int totalMoves = 0;
    for (int i = 0; i < s.size(); ++i) {
        // Convert characters to their respective positions in the alphabet (0-based index)
        int start = s[i] - 'a';
        int end = f[i] - 'a';
        // Calculate forward and backward distances
        int forwardMove = abs(end - start);
        int backwardMove = 26 - forwardMove;
        // The minimal moves for this character
        totalMoves += min(forwardMove, backwardMove);
    }

    cout << totalMoves << endl;
    return 0;
}