Also you are missing a period after 'moon'

The tests don't accept the oxford comma - which they really should :)

I also was stumped by this, but understand now. Range returns a sequence between two numbers, so if there is no step/sequence between the two numbers, then there is subsequent number to return. Therefore, only one value is returned.

My test is failing?! but the answer is correct..

It says:
Test Results:

Testing for instance porsche of class Vehicle...
"Hi, I'm one of those Vehicles! Have a look at my engine, seats, and wheels." should equal "Hi, I'm one of those Vehicles! Have a look at my engine, seats and wheels."

Testing for instance earth of Planet...
"Hi, I'm one of those Planets! Have a look at my moon" should equal "Hi, I'm one of those Planets! Have a look at my moon."

Amazing

I still don't understand the description... there are a few strange English phrases. Can I suggest something like this?

You can see below I have changed some tenses, and some wordings.

Introduction

Little Petya very much likes sequences. However, recently he received a sequence as a gift from his mother. Petya didn't like it at all! He decided to make a single replacement. After this replacement, Petya would like to the sequence in increasing order.

He asks himself: What is the lowest possible value I could have got...(got from... the total? got from where?) after making the replacement and sorting the sequence?

About the replacement:

Choose exactly one element from the sequence, and replace it with another integer > 0. You are not allowed to replace a number with itself, or to change no number at all.

Task:

Find the lowest possible sequence after performing a valid replacement, and sorting the sequence.

Input:

Input contains sequence with N integers. All elements of the sequence > 0. The sequenc will never be empty.

Output:

Return sequence with N integers — which includes the lowest possible values of each sequence element, after the single replacement and sorting has been performed.