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

string s,f;
int sum;
int main (){
	//freopen("controller.in","r",stdin);
	freopen("controller.out","w",stdout);
	int i,j;
	cin>>s;
	cin>>f;
	for(i=0; i<f.size(); i++)
	{			
        int d=abs(s[i]-f[i]);
        sum += min(d,26-d);
	}
	cout<<sum;

	
	return 0;
}