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

Input: Consider Input: Sentence: 'a couple of boys in a field playing baseball'. Find frequency of the letter 'i'

Output: 3


Input: Consider Input: Sentence: 'a picture of two men on a motorcycle in front of a railroad track'. Find frequency of the letter 'n'

Output: 4


Input: Consider Input: Sentence: 'a brown bear is wading in choppy gray water'. Find frequency of the letter 'o'


Output: 2