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

Example Input: Sentence: 'a motorcycle sitting on the side of the road by grass'. Replace the letter 'r' with 't' in the sentence.
Example Output: a mototcycle sitting on the side of the toad by gtass

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: 'a person standing on a jet ski in the water'. Replace the letter 'n' with 'r' in the sentence.
Example Output:
a persor stardirg or a jet ski ir the water