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

Input: Consider Input: Sentence: 'a couple of giraffe standing next to each other in a forest'. Replace the letter 'a' with 'w' in the sentence.

Output: w couple of girwffe stwnding next to ewch other in w forest

Input: Consider Input: Sentence: 'a dog wearing a pink life jacket sitting on a surf board in the ocean'. Replace the letter 'c' with 'y' in the sentence.

Output: a dog wearing a pink life jayket sitting on a surf board in the oyean

Input: Consider Input: Sentence: 'a fast commuter train sits parked next to a train depot'. Replace the letter 'm' with 'z' in the sentence.
Output: a fast cozzuter train sits parked next to a train depot