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

Input: Consider Input: Sentence: 'seagulls sit on the posts of a seaside balcony by a clock tower'. Find frequency of the letter 'g'

Output: 1

Input: Consider Input: Sentence: 'a black cat laying down on a bed'. Find frequency of the letter 'y'

Output: 1

Input: Consider Input: Sentence: 'stacks of pizzas in pans on a rack waiting to be cooked'. Find frequency of the letter 's'
Output: 4