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

Ex Input:
Sentence: 'a couple giraffes walking through a fielded area'. Replace the letter 'e' with 'c' in the sentence.

Ex Output:
a couplc giraffcs walking through a ficldcd arca

Ex Input:
Sentence: 'a pile of chopped up broccoli sits next to bottles of sauces'. Replace the letter 't' with 'y' in the sentence.

Ex Output:
a pile of chopped up broccoli siys nexy yo boyyles of sauces

Ex Input:
Sentence: 'the car is waiting for the train to pass before crossing'. Replace the letter 't' with 'c' in the sentence.

Ex Output:
che car is waicing for che crain co pass before crossing