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

Input: Consider Input: Sentence: 'a bathroom with a sink, counter top, and mirror is shown'. Find frequency of the letter 'i'

Output: 4


Input: Consider Input: Sentence: 'a log in the water with three birds perched on it'. Find frequency of the letter 'r'

Output: 4


Input: Consider Input: Sentence: 'a passenger bus and a car driving through a street'. Find frequency of the letter 'a'


Output: 6