Problem states that rod has length N and it contradicts itself by saying that it has left end at x = 0 and right end = N , which means rod length = N - 0 + 1 = N+1

eg : a rod from 0 to 5 will be of 6 length.

Problem states that rod has length N and it contradicts itself by saying that it has left end at x = 0 and right end = N , which means rod length = N - 0 + 1 = N+1

eg : a rod from 0 to 5 will be of 6 length.

No it will be of length 5 only. You are actually counting no of elements in (0,5) … but think of it as a continuous measurement scale which starts from 0…