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

Ex Input:
Sentence: 'this is a cute dog sticking his head out of the window of a red car'. Replace the letter 'e' with 'z' in the sentence.

Ex Output:
this is a cutz dog sticking his hzad out of thz window of a rzd car

Ex Input:
Sentence: 'an elephant in chains converses with a smaller elephant who is not wearing chains'. Replace the letter 'i' with 'm' in the sentence.

Ex Output:
an elephant mn chamns converses wmth a smaller elephant who ms not wearmng chamns

Ex Input:
Sentence: 'a castle wall with a square black clock'. Replace the letter 'a' with 'y' in the sentence.

Ex Output:
y cystle wyll with y squyre blyck clock