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

Ex Input:
Sentence: 'an old rusty car sits outside of an old building'. Replace the letter 'o' with 'r' in the sentence.

Ex Output:
an rld rusty car sits rutside rf an rld building


Ex Input:
Sentence: 'a polar bear relaxing in a man-made pool'. Replace the letter 'r' with 'x' in the sentence.

Ex Output:
a polax beax xelaxing in a man-made pool


Ex Input:
Sentence: 'there is no image on this page to describe'. Replace the letter 'd' with 'e' in the sentence.

Ex Output:

there is no image on this page to eescribe