Each letter in the word HARMFUL is arranged in the English alphabetical order. How many letters are there in the English alphabetical order between the letter which is third from the left end and the one which is third from the right end in the new letter-cluster thus formed?

Given: HARMFUL

Letters: H, A, R, M, F, U, L
Arranged alphabetically:
A, F, H, L, M, R, U

3rd from the left → H

3rd from the right → Let's count from right:

1st from right: U

2nd from right: R

3rd from right: M

So, the two letters are H and M

English Alphabet Series: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

I (1), J (2), K (3), L (4)

4 letters in between