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

Input: Consider Input: Sentence: 'a white bathroom sink sitting next to a toilet'. Find frequency of the letter 'i'

Output: 5


Input: Consider Input: Sentence: 'a bird in a tree looking up at branches'. Find frequency of the letter 'e'

Output: 3


Input: Consider Input: Sentence: 'people riding motorcycles on a city  with people on the side walk'. Find frequency of the letter 'a'


Output: 2