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

Example Input: Sentence: 'a couple of giraffe standing next to each other'. Replace the letter 'i' with 'q' in the sentence.
Example Output: a couple of gqraffe standqng next to each other

Example Input: Sentence: 'a red train moves over snowy rail road tracks'. Replace the letter 'v' with 'w' in the sentence.
Example Output: a red train mowes ower snowy rail road tracks

Example Input: Sentence: 'several kids playing soccer in front of parked cars'. Replace the letter 'e' with 'a' in the sentence.
Example Output:
savaral kids playing soccar in front of parkad cars