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

Example Input: Sentence: 'a tower type building structure with a large clock and many windows in front of a cloudy blue sky'. Replace the letter 'n' with 'x' in the sentence.
Example Output: a tower type buildixg structure with a large clock axd maxy wixdows ix froxt of a cloudy blue sky

Example Input: Sentence: 'a hand held game or older cell phone'. Replace the letter 'o' with 'c' in the sentence.
Example Output: a hand held game cr clder cell phcne

Example Input: Sentence: 'there are three people posing for a picture with dogs'. Replace the letter 'e' with 's' in the sentence.
Example Output:
thsrs ars thrss psopls posing for a picturs with dogs