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

Example Input: Sentence: 'a boy taking a nap with his dog on a bed'. Replace the letter 'o' with 'i' in the sentence.
Example Output: a biy taking a nap with his dig in a bed

Example Input: Sentence: 'a man that is on the back of an elephant'. Replace the letter 'c' with 'd' in the sentence.
Example Output: a man that is on the badk of an elephant

Example Input: Sentence: 'man in black wetsuit walking on the beach with a white surfboard'. Replace the letter 'n' with 'p' in the sentence.
Example Output:
map ip black wetsuit walkipg op the beach with a white surfboard