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

Input: Consider Input: Sentence: 'a number of small boats on a beach near an umbrella'. Find frequency of the letter 's'

Output: 2


Input: Consider Input: Sentence: 'a woman holds some baked goods at the convention'. Find frequency of the letter 'd'

Output: 3


Input: Consider Input: Sentence: 'a pizza with cheese, mushrooms, and strips of prosciutto'. Find frequency of the letter 'i'


Output: 4