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

Input: Consider Input: Sentence: 'a stop sign next to houses with christmas lights'. Find frequency of the letter 's'

Output: 7


Input: Consider Input: Sentence: 'a man serving himself pizza in a wooden booth'. Find frequency of the letter 'n'

Output: 4


Input: Consider Input: Sentence: 'a desk top compter is on the desk'. Find frequency of the letter 'r'


Output: 1