Hi I cannot understand why the best case for line 3 is `n-1` and why it isnt just always `n`?

I tried to write this in python to understand when it would be `n-1` and the answer is always `n`. I am assuming that the loop counter in pseudo-code is evaluated one more time than the body is executed as is said in the Cormen book.

My thinking is that if the length of `n` is 1, the loop evaluation is still tested so regardless the answer would still be `n`, even if the loop body itself did not run.

```
Max(A)

1 MaxInt = A[1]
2 index = 2
3 while index ≤ n // Why is the best n-1 here?
4   if MaxInt < A[index]
5     MaxInt = A[index]
6   index = index+1
7 return MaxInt

```

I know it has to be something very simple but I cant seem to work it out as testing with 1 or 1000 the answer I get back for a count is always `n-1` (0, 999) and if I assume that the loops asserts a final time that is + 1, so `0 + 1 = 1`, which is `n` and `999 + 1 = 1000` which is `n`.