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