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

Sentence: 'group of snowboarders on a snowy trail overlooking a mountain'. Find frequency of the letter 'r'
5

Sentence: 'a player swings his bat at a baseball game'. Find frequency of the letter 'p'
1

Sentence: 'two giraffes locked inside of a small cage'. Find frequency of the letter 's'

3