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

Input: Consider Input: Sentence: 'a herd of horses standing next to each other on a field'. Find frequency of the letter 'r'

Output: 3


Input: Consider Input: Sentence: 'a couple is cutting in to a cake at a wedding'. Find frequency of the letter 'd'

Output: 2


Input: Consider Input: Sentence: 'a girl in a green shirt and hat being defended by a girl in a white dress while playing frisbee'. Find frequency of the letter 'r'


Output: 6