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

Example Input: Sentence: 'a man walking a horse on a dirt track'. Replace the letter 't' with 's' in the sentence.
Example Output: a man walking a horse on a dirs srack

Example Input: Sentence: 'a man holds his hands out in pursuit of a disk'. Replace the letter 'n' with 'o' in the sentence.
Example Output: a mao holds his haods out io pursuit of a disk

Example Input: Sentence: 'a clock tower reaches us into the sky'. Replace the letter 'o' with 'm' in the sentence.
Example Output:
a clmck tmwer reaches us intm the sky