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

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: 'an overhead view of a city cross walk on a rainy day features an array of colorful umbrellas'. Replace the letter 's' with 'd' in the sentence.
Example Output: an overhead view of a city crodd walk on a rainy day featured an array of colorful umbrellad

Example Input: Sentence: 'tall block tower with clock faces and windows on partly cloudy day'. Replace the letter 'w' with 'p' in the sentence.
Example Output:
tall block toper pith clock faces and pindops on partly cloudy day