How many such pairs of letters are there in the word 'HISTORICAL' which have as many letters between them in the word as they have between them in the English alphabet?

Explanation

Total Six Pairs They are: 1) HI 2) ST 3) I L 4) LS 5) CI 6) RT *Note that in these six pairs of words the difference in alphabets in-between the letter 'HISTORICAL' and in English alphabets is the same. For example: The alphabets H and I have zero alphabets in between the letter HISTORICAL and zero in English alphabets (A-Z). Same is the case for Pair No 2: (ST). Similarly Pair 3 (IL) have a difference of 2 alphabets in both the letter HISTORICAL and in English alphabets (A-Z). The other 3 follow similar sequence but in a backwards direction. Means the counting should be made from right to left side.