In this task, you need to replace a letter in the sentence with another given letter.

Example Input: Sentence: 'the kitchen has a big screen tv and a lot of counter space'. Replace the letter 'h' with 'z' in the sentence.
Example Output: tze kitczen zas a big screen tv and a lot of counter space

Example Input: Sentence: 'a group of people on a beach flying a kite'. Replace the letter 'p' with 'i' in the sentence.
Example Output: a groui of ieoile on a beach flying a kite

Example Input: Sentence: 'three white sheep walking down a town road'. Replace the letter 'n' with 'z' in the sentence.
Example Output:
three white sheep walkizg dowz a towz road