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

Example Input: Sentence: 'a white bathroom with a stand alone sink and a shower curtain'. Replace the letter 'a' with 'm' in the sentence.
Example Output: m white bmthroom with m stmnd mlone sink mnd m shower curtmin

Example Input: Sentence: 'a spacious bedroom with tidy bed and sofa with cushions'. Replace the letter 'n' with 'c' in the sentence.
Example Output: a spacious bedroom with tidy bed acd sofa with cushiocs

Example Input: Sentence: 'a man on red skis on a high slope overlooking mountains'. Replace the letter 'a' with 'x' in the sentence.
Example Output:
x mxn on red skis on x high slope overlooking mountxins