( Problem A ) Pikachu and the Game of Strings
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## Algorithms, Greedy Algorithms

Problem
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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 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
SAMPLE INPUT
4
ABCT
PBDI

SAMPLE OUTPUT
7

Explanation

Pikachu can convert move s into t in 7 days as follows:

1. $A -> N$ (1st letter)
2.  $N -> O$ (1st letter)
3.  $O -> P$ (1st letter)
4. $C -> D$ (3rd letter)
5. $T -> G$ (4th letter)
6. $G -> H$ (4th letter)
7. $H -> I$ (4th letter)
Time Limit: 1.0 sec(s) for each input file.
Memory Limit: 256 MB
Source Limit: 1024 KB

## This Problem was Asked in

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