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

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 woman in a dining-room holding a knife, cutting a cake on the table'. Replace the letter 'i' with 'p' in the sentence.
Example Output: a woman pn a dpnpng-room holdpng a knpfe, cuttpng a cake on the table

Example Input: Sentence: 'a curved desk with  keyboard and monitor on it'. Replace the letter 'r' with 'y' in the sentence.
Example Output:
a cuyved desk with  keyboayd and monitoy on it