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

Example Input: Sentence: 'a crowd looking at a trio of planes that are sitting idle'. Replace the letter 'a' with 'e' in the sentence.
Example Output: e crowd looking et e trio of plenes thet ere sitting idle

Example Input: Sentence: 'a giraffe standing alone with a low fence behind it'. Replace the letter 't' with 'o' in the sentence.
Example Output: a giraffe soanding alone wioh a low fence behind io

Example Input: Sentence: 'a man is swinging a bat as a man squats to catch the ball while the crowd watches behind them'. Replace the letter 'c' with 's' in the sentence.
Example Output:
a man is swinging a bat as a man squats to satsh the ball while the srowd watshes behind them