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

Ex Input:
Sentence: 'two men and a dog are standing beside a building'. Replace the letter 'b' with 'y' in the sentence.

Ex Output:
two men and a dog are standing yeside a yuilding

Ex Input:
Sentence: 'a open entrance leading to a set of closed doors'. Replace the letter 'd' with 'f' in the sentence.

Ex Output:
a open entrance leafing to a set of closef foors

Ex Input:
Sentence: 'two brown bowls filled with food sitting on a counter'. Replace the letter 'i' with 'm' in the sentence.

Ex Output:
two brown bowls fmlled wmth food smttmng on a counter