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

Input: Consider Input: Sentence: 'two elephants walking on cement next to wall'. Find frequency of the letter 'n'

Output: 5


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

Output: 2


Input: Consider Input: Sentence: 'a desk has a laptop on it that is turned on'. Find frequency of the letter 'a'


Output: 5