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

Example Input: Sentence: 'a house cat sits on an oven door, sniffing the oven racks inside'. Replace the letter 'i' with 'y' in the sentence.
Example Output: a house cat syts on an oven door, snyffyng the oven racks ynsyde

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 woman approaches the finish line on skis'. Replace the letter 'm' with 'c' in the sentence.
Example Output:
a wocan approaches the finish line on skis