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

Input: Consider Input: Sentence: 'a double-decker bus covered in children's illustrations driving next to a van'. Find frequency of the letter 'a'

Output: 4


Input: Consider Input: Sentence: 'different sets of luggage in a baggage claim area'. Find frequency of the letter 'r'

Output: 2


Input: Consider Input: Sentence: 'a bright red umbrella protects a walker from the rain at night'. Find frequency of the letter 'e'


Output: 5