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: 'giraffe looking tired as it sticks its neck out through the fence'. Reverse all words of length '5' in the given sentence.

giraffe looking derit as it sticks its neck out through the ecnef