Pikachu has recently learnt a new move $s$. He knows he can work hard and convert it into a stronger move $t$. Both the moves $s$ and $t$ contain the same number of letters.

In a single day, Pikachu can increase any letter of move $s$ by one, that is, in a single day, he can convert letter $A$ to $B$, $C$ to $D$, $M$ to $N$ and so on. He can also convert letter $Z$ to letter $A$. 

Pikachu just realized he also has a hidden ability. It can help him increase any letter of move $s$ by $13$,  that is, in a single day, he can convert letter $A$ to letter $N$, $B$ into $O$, $M$ into $Z$ , $O$ into $B$ and so on.  

Now Pikachu wants to know the minimum number of days in which he can convert the move $s$ into move $t$  ?
 

Constraints:

• $1\le |s|=|t|\le 10^5$
• s and t consists of uppercase English letters only

Input format:

• First line contains an integer $n$, the length of strings $s$ and $t$
• Second line contains string $s$ of length $n$
• Third line contains string $t$ of length $n$ 

Output format:

• Output single line containing the minimum number of days required