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

Ex Input:
Sentence: 'a close shot of a stop sign near a building'. Replace the letter 'b' with 'u' in the sentence.

Ex Output:
a close shot of a stop sign near a uuilding


Ex Input:
Sentence: 'a dog drinking out of a bowl of water'. Replace the letter 'w' with 'k' in the sentence.

Ex Output:
a dog drinking out of a bokl of kater


Ex Input:
Sentence: 'an old red fire truck is parked on gravel'. Replace the letter 'e' with 'n' in the sentence.

Ex Output:

an old rnd firn truck is parknd on gravnl