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

Example Input: Sentence: 'a person on a snow board flying through the air'. Replace the letter 'f' with 'n' in the sentence.
Example Output: a person on a snow board nlying through the air

Example Input: Sentence: 'a book shelf full of books and nick nacks '. Replace the letter 'o' with 'm' in the sentence.
Example Output: a bmmk shelf full mf bmmks and nick nacks 

Example Input: Sentence: 'a mexican-style pizza sits on a plate with a knife and small cups of salsa and sour cream'. Replace the letter 'e' with 'd' in the sentence.
Example Output:
a mdxican-styld pizza sits on a platd with a knifd and small cups of salsa and sour crdam