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

Example Input: Sentence: 'a shot looks down on a person riding a long board'. Replace the letter 'o' with 'u' in the sentence.
Example Output: a shut luuks duwn un a persun riding a lung buard

Example Input: Sentence: 'an old photo of group of people nicely dressed around the end of a long table'. Replace the letter 'e' with 'i' in the sentence.
Example Output: an old photo of group of piopli nicily drissid around thi ind of a long tabli

Example Input: Sentence: 'two zebras and two giraffes graze on grass'. Replace the letter 'n' with 'o' in the sentence.
Example Output:
two zebras aod two giraffes graze oo grass