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

Input: Consider Input: Sentence: 'a small doughnut held in a persons hand'. Find frequency of the letter 'n'

Output: 4


Input: Consider Input: Sentence: 'two persons standing outside a moving sub train'. Find frequency of the letter 'a'

Output: 3


Input: Consider Input: Sentence: 'a giraffe moving its head up to graze on some leaves'. Find frequency of the letter 's'


Output: 3