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

Input: Consider Input: Sentence: 'a boy catching a frisbee while standing ins bunch of leaves'. Find frequency of the letter 'a'

Output: 5

Input: Consider Input: Sentence: 'a piece of bread stuffed with meat and vegetables'. Find frequency of the letter 's'

Output: 2

Input: Consider Input: Sentence: 'a cargo plane being loaded by a scissor jack truck'. Find frequency of the letter 'b'
Output: 2