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

Input: Consider Input: Sentence: 'the sun goes down over a bike tied to a bench at the beach'. Find frequency of the letter 't'

Output: 5

Input: Consider Input: Sentence: 'a man with a large grey and black beard and glasses and a tie'. Find frequency of the letter 'e'

Output: 5

Input: Consider Input: Sentence: 'a bed with a wooden head board and a lamp next to it'. Find frequency of the letter 'n'
Output: 3