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

Ex Input:
Sentence: 'subway train approaching the platform of a subway station'. Replace the letter 'y' with 'c' in the sentence.

Ex Output:
subwac train approaching the platform of a subwac station


Ex Input:
Sentence: 'a dog laying in front of a horses stall with the horse peeking over the half door'. Replace the letter 'a' with 'b' in the sentence.

Ex Output:
b dog lbying in front of b horses stbll with the horse peeking over the hblf door


Ex Input:
Sentence: 'the man is sitting down talking on his cell phone'. Replace the letter 't' with 'o' in the sentence.

Ex Output:

ohe man is siooing down oalking on his cell phone