Definition: In this task, you need to reverse all words of a given length in the sentence. The number of letters in a word determine its length. For example, the length of the word "apple" is 5.
Input: Sentence: 'a dog laying on its side on the floor next to a teddy bear'. Reverse all words of length '5' in the given sentence.

a dog laying on its side on the roolf next to a yddet bear