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

Input: Consider Input: Sentence: 'a couple of men sitting next to each other under an umbrella'. Find frequency of the letter 'n'

Output: 5


Input: Consider Input: Sentence: 'supplies and tools are arranged on the floor with a hard hat and bag'. Find frequency of the letter 'n'

Output: 4


Input: Consider Input: Sentence: 'a street sign that is covered in stickers on the back'. Find frequency of the letter 's'


Output: 5