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

Input: Consider Input: Sentence: 'a bus is driving on the street behind some cars'. Find frequency of the letter 'a'

Output: 2


Input: Consider Input: Sentence: 'a person does a trick on a ramp on a snowboard'. Find frequency of the letter 's'

Output: 3


Input: Consider Input: Sentence: 'a baseball player who is stepping up to home plate'. Find frequency of the letter 's'


Output: 3