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: 'two police officers are on motorcycles and people are milling about on the side walk'. Reverse all words of length '5' in the given sentence.

two police officers are on motorcycles and people are milling tuoba on the side walk