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

Input: Consider Input: Sentence: 'a bird in a tree looking up at branches'. Find frequency of the letter 'e'

Output: 3

Input: Consider Input: Sentence: 'a truck with a camper sits parked in some vegetation'. Find frequency of the letter 's'

Output: 3

Input: Consider Input: Sentence: 'two bears laying together out on the grass'. Find frequency of the letter 't'
Output: 5