In this task, you need to count the number of times the given letter appears in the given sentence.

Sentence: 'large grassy pasture filled with trees and a single horse'. Find frequency of the letter 'l'
4

Sentence: 'a dog on a couch near many pillows'. Find frequency of the letter 'p'
1

Sentence: 'a young woman in a blue dress walks with a young man'. Find frequency of the letter 'n'

5