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

Example Input: Sentence: 'a group of young adults are engaged in outdoor exercise'. Replace the letter 'g' with 'n' in the sentence.
Example Output: a nroup of younn adults are ennaned in outdoor exercise

Example Input: Sentence: 'traffic congestion with cars and an electric tram'. Replace the letter 'a' with 'k' in the sentence.
Example Output: trkffic congestion with ckrs knd kn electric trkm

Example Input: Sentence: 'a woman sits on a motorcycle next to more motorcycles and people outside of buildings'. Replace the letter 'p' with 'i' in the sentence.
Example Output:
a woman sits on a motorcycle next to more motorcycles and ieoile outside of buildings