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

Example Input: Sentence: 'a safari setting at a zoo with two giraffes and a zebra'. Replace the letter 'n' with 'g' in the sentence.
Example Output: a safari settigg at a zoo with two giraffes agd a zebra

Example Input: Sentence: 'a man and a child skiing down a mountain on a trail'. Replace the letter 'n' with 'm' in the sentence.
Example Output: a mam amd a child skiimg dowm a moumtaim om a trail

Example Input: Sentence: 'a sandy beach covered in lots of flying kites'. Replace the letter 'l' with 'o' in the sentence.
Example Output:
a sandy beach covered in oots of foying kites