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

Input: Consider Input: Sentence: 'a person riding a skate board on a city street'. Find frequency of the letter 'a'

Output: 5


Input: Consider Input: Sentence: 'a couple is cutting in to a cake at a wedding'. Find frequency of the letter 'd'

Output: 2


Input: Consider Input: Sentence: 'a building sitting along side of a street'. Find frequency of the letter 'e'


Output: 3