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

Input: Consider Input: Sentence: 'two men sitting quietly on a park bench'. Find frequency of the letter 'a'

Output: 2


Input: Consider Input: Sentence: 'a crowd of people skiing and enjoying the snow'. Find frequency of the letter 'o'

Output: 5


Input: Consider Input: Sentence: 'this is a duck with its face in the water'. Find frequency of the letter 's'


Output: 3