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

Example Input: Sentence: 'a group of people walking along a dirty snow covered road'. Replace the letter 'n' with 'i' in the sentence.
Example Output: a group of people walkiig aloig a dirty siow covered road

Example Input: Sentence: 'a small child reaching back with a wii remote'. Replace the letter 'l' with 'o' in the sentence.
Example Output: a smaoo chiod reaching back with a wii remote

Example Input: Sentence: 'the view of a field from a bus driving down a dirt road'. Replace the letter 'd' with 'r' in the sentence.
Example Output:
the view of a fielr from a bus rriving rown a rirt roar