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

Input: Consider Input: Sentence: 'a car accident has slowed traffic as a clean up crew works'. Find frequency of the letter 'f'

Output: 2


Input: Consider Input: Sentence: 'three young children playing with a ball in front of a huge bridge'. Find frequency of the letter 'e'

Output: 5


Input: Consider Input: Sentence: 'there's a large clock tower and some building landscape'. Find frequency of the letter 'd'


Output: 3