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

Input: Consider Input: Sentence: 'a grey hummingbird by fence and tree branches'. Find frequency of the letter 'y'

Output: 2


Input: Consider Input: Sentence: 'two zebras standing around while a third zebra drinks from a pond'. Find frequency of the letter 's'

Output: 3


Input: Consider Input: Sentence: 'a dog sitting on a bed looking out of a window'. Find frequency of the letter 'w'


Output: 2