instruction:
In this task, you need to replace a letter in the sentence with another given letter.
question:
Sentence: 'people wait for a train on a snowy sidewalk'. Replace the letter 'n' with 'm' in the sentence.
answer:
people wait for a traim om a smowy sidewalk


question:
Sentence: 'a long green grain traveling past a white building'. Replace the letter 'w' with 'o' in the sentence.
answer:
a long green grain traveling past a ohite building


question:
Sentence: 'many people wait to get tickets at a train station'. Replace the letter 'c' with 'u' in the sentence.
answer:

many people wait to get tiukets at a train station