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

Input: Consider Input: Sentence: 'a man on stiltz is standing under a pink umbrella'. Find frequency of the letter 's'

Output: 3


Input: Consider Input: Sentence: 'a blue tripocal bird is perched on a wooden fence'. Find frequency of the letter 'd'

Output: 3


Input: Consider Input: Sentence: 'a kitchen filled with a center island made out of wood'. Find frequency of the letter 'a'


Output: 4