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

Input: Consider Input: Sentence: 'a girl sits on a surfboard and smiles'. Find frequency of the letter 'i'

Output: 3


Input: Consider Input: Sentence: 'a blue train on a track next to another track'. Find frequency of the letter 'c'

Output: 2


Input: Consider Input: Sentence: 'a group of young men with frisbees standing next to barn'. Find frequency of the letter 'r'


Output: 3