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

Input: Consider Input: Sentence: 'a police officer who is riding on a horse'. Find frequency of the letter 'p'

Output: 1


Input: Consider Input: Sentence: 'a person that is looking out his window'. Find frequency of the letter 'n'

Output: 3


Input: Consider Input: Sentence: 'a teddy bear hanging from a tree and a car parked next to it'. Find frequency of the letter 'd'


Output: 4