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

Ex Input:
Sentence: 'some brown black and white horses clouds and rocks'. Replace the letter 'a' with 'n' in the sentence.

Ex Output:
some brown blnck nnd white horses clouds nnd rocks

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 blender sitting next to a field full of grass'. Replace the letter 't' with 'n' in the sentence.

Ex Output:
a blender sinning nexn no a field full of grass