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 swinging a bat while playing baseball'. Find frequency of the letter 'h'

Output: 1

Input: Consider Input: Sentence: 'a large group of motorcycles parked along a street'. Find frequency of the letter 'a'

Output: 5

Input: Consider Input: Sentence: 'a bathroom shelf with a toothbrush and a toothpaste tube'. Find frequency of the letter 'f'
Output: 1