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 male and female skier posing at the top of a hill in front of snowy mountains'. Reverse all words of length '4' in the given sentence.

a elam and female skier posing at the top of a llih in front of snowy mountains