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

Sentence: 'man is snow gear and skis skiing in the snow'. Find frequency of the letter 'i'
5

Sentence: 'flower in a vase full of water sitting on a stand '. Find frequency of the letter 'l'
3

Sentence: 'a brown piano sitting in a living room next to a book shelf'. Find frequency of the letter 'f'

1