Anagrams

Elly has two strings of the same length $A$ and $B$. Now she wants to transform $A$ into an anagram of $B$ by changing some of its letters.Definition: We call two strings $X$ and $Y$ anagrams of each-other if we can re-arrange the letters in one of them to get the other.The only operation the girl can make is cyclically increment one or more times some (possibly none or all) of the characters in $A$. Example increments are 'A' to 'B', 'K' to 'L' or 'Z' to 'A'.For example, she can transform "ELLY" to "KRIS" character by character by shifting 'E' to 'K' ($6$ operations), 'L' to 'R' (again $6$ operations), the second 'L' to 'I' ($23$ operations, going from 'Z' to 'A' on the $15$-th operation), and finally 'Y' to 'S' ($20$ operations, again cyclically going from 'Z' to 'A' on the $2$-nd operation). The total number of operations would be 6 + 6 + 23 + 20 = 55. However, to make "ELLY" an anagram of "KRIS" it would be better to change it to "IRSK" with only $29$ operations.

You are given the strings $A$ and $B$. Write a program which calculates the minimal number of operations needed to transform $A$ into some other string $X$, such that $X$ is an anagram of $B$.