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

Input: Consider Input: Sentence: 'a young man riding a skateboard near a forest'. Find frequency of the letter 'd'

Output: 2

Input: Consider Input: Sentence: 'a tall building with antenna stands before a jet flying in the background'. Find frequency of the letter 't'

Output: 6

Input: Consider Input: Sentence: 'a man paddle boards near the shore while birds fly nearby'. Find frequency of the letter 'm'
Output: 1