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 couple of men sitting next to each other under an umbrella'. Find frequency of the letter 'n'

Output: 5


Input: Consider Input: Sentence: 'an asian airlines airplane near the taxi runway'. Find frequency of the letter 'n'


Output: 6