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

Input: Consider Input: Sentence: 'a dog is shown sitting on rocks by the beach'. Find frequency of the letter 'a'

Output: 2


Input: Consider Input: Sentence: 'two people under an umbrella while walking down a sidewalk'. Find frequency of the letter 'i'

Output: 3


Input: Consider Input: Sentence: 'a family sitting together on the beach'. Find frequency of the letter 'f'


Output: 1