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

Ex Input:
Sentence: 'a small bird perched on some thin branches'. Replace the letter 'a' with 'f' in the sentence.

Ex Output:
f smfll bird perched on some thin brfnches


Ex Input:
Sentence: 'vita mix blender with something in it already blended'. Replace the letter 'b' with 'a' in the sentence.

Ex Output:
vita mix alender with something in it already alended


Ex Input:
Sentence: 'a person standing in the rain with an umbrella'. Replace the letter 'i' with 'f' in the sentence.

Ex Output:

a person standfng fn the rafn wfth an umbrella