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

Ex Input:
Sentence: 'a group of giraffe standing on top of a dirt field'. Replace the letter 'a' with 'y' in the sentence.

Ex Output:
y group of giryffe stynding on top of y dirt field


Ex Input:
Sentence: 'a baseball player is throwing a ball across the dirt field'. Replace the letter 'a' with 't' in the sentence.

Ex Output:
t btsebtll pltyer is throwing t btll tcross the dirt field


Ex Input:
Sentence: 'five zebras stand in a group near a patch of scrub'. Replace the letter 'b' with 'y' in the sentence.

Ex Output:

five zeyras stand in a group near a patch of scruy