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

Example Input: Sentence: 'a black cat is sniffing a glass bottle'. Replace the letter 'c' with 'f' in the sentence.
Example Output: a blafk fat is sniffing a glass bottle

Example Input: Sentence: 'a man taking a photo of food on a table'. Replace the letter 't' with 'h' in the sentence.
Example Output: a man haking a phoho of food on a hable

Example Input: Sentence: 'a man walking down the block with an umbrella'. Replace the letter 'n' with 'f' in the sentence.
Example Output:
a maf walkifg dowf the block with af umbrella