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

Ex Input:
Sentence: 'a photo of a river with a train bridge across it'. Replace the letter 'r' with 'f' in the sentence.

Ex Output:
a photo of a fivef with a tfain bfidge acfoss it


Ex Input:
Sentence: 'a u.s. military helicopter landing or taking off'. Replace the letter 'i' with 'l' in the sentence.

Ex Output:
a u.s. mllltary hellcopter landlng or taklng off


Ex Input:
Sentence: 'a young man sitting on a bus up against a window'. Replace the letter 's' with 'j' in the sentence.

Ex Output:

a young man jitting on a buj up againjt a window