TASK DEFINITION: In this task, you need to replace a letter in the sentence with another given letter.
PROBLEM: Sentence: 'a couple sits on a bench in the countryside'. Replace the letter 'y' with 'k' in the sentence.

SOLUTION: a couple sits on a bench in the countrkside

PROBLEM: Sentence: 'a man is on a bed with a cat and laptop computer'. Replace the letter 'e' with 'n' in the sentence.

SOLUTION: a man is on a bnd with a cat and laptop computnr

PROBLEM: Sentence: 'a tall white building under a cloudy gray sky'. Replace the letter 'e' with 'o' in the sentence.

SOLUTION:
a tall whito building undor a cloudy gray sky