Length

If both left and right are included (inclusive range), then:

• Length = right - left + 1
• Example: left = 2, right = 5 ⇒ elements are 2,3,4,5 ⇒ length = 5 - 2 + 1 = 4
• If right < left, the range is empty ⇒ length is 0 (usually, depending on your definition).