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

Input: Consider Input: Sentence: 'an image of a cautionary construction sign'. Find frequency of the letter 'a'

Output: 5


Input: Consider Input: Sentence: 'a man standing on a surf board in the ocean'. Find frequency of the letter 'f'

Output: 1


Input: Consider Input: Sentence: 'a large kitchen with brown cabinets and a sky light'. Find frequency of the letter 'k'


Output: 2