TASK DEFINITION: In this task, you need to replace a letter in the sentence with another given letter.
PROBLEM: Sentence: 'people wait for a train on a snowy sidewalk'. Replace the letter 'n' with 'm' in the sentence.

SOLUTION: people wait for a traim om a smowy sidewalk

PROBLEM: Sentence: 'two cats sitting on an office chair next to a desk'. Replace the letter 's' with 'j' in the sentence.

SOLUTION: two catj jitting on an office chair next to a dejk

PROBLEM: Sentence: 'a surfer lies prone on his board in a wave'. Replace the letter 'r' with 'w' in the sentence.

SOLUTION:
a suwfew lies pwone on his boawd in a wave