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

Input: Consider Input: Sentence: 'a woman and a child walking down a street with a kite'. Find frequency of the letter 'n'

Output: 4

Input: Consider Input: Sentence: 'a cat sleeping near lots of pairs of shoes'. Find frequency of the letter 'r'

Output: 2

Input: Consider Input: Sentence: 'the large adult elephant walks through the grassy water'. Find frequency of the letter 'g'
Output: 3