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

Example Input: Sentence: 'a rare picture of an individual within this image'. Replace the letter 'd' with 'z' in the sentence.
Example Output: a rare picture of an inzivizual within this image

Example Input: Sentence: 'a u.s. military helicopter landing or taking off'. Replace the letter 'i' with 'l' in the sentence.
Example Output: a u.s. mllltary hellcopter landlng or taklng off

Example Input: Sentence: 'woman in front with black bag at her side. second woman entering behind'. Replace the letter 'a' with 'p' in the sentence.
Example Output:
wompn in front with blpck bpg pt her side. second wompn entering behind