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

Input: Consider Input: Sentence: 'a man with headphones on is hunched over a sink while being recorded'. Find frequency of the letter 'd'

Output: 4

Input: Consider Input: Sentence: 'a man riding a white surfboard on a large wave'. Find frequency of the letter 'a'

Output: 7

Input: Consider Input: Sentence: 'a woman sitting on top of a red bench next to a man on a bike'. Find frequency of the letter 't'
Output: 5