How many letters of the English alphabet stand between the fifth letter from the left end and the eighth letter from the right end?

The fifth letter from the left is E, at place 5; the eighth from the right is at place 26 − 8 + 1 = 19, which is S. The letters strictly between them run from place 6 to place 18, which is 18 − 6 + 1 = 13 letters. Counting one of the two named letters as well gives 14, counting both gives 15, and stopping a place short at S taken as place 18 gives 12.