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

Input: Consider Input: Sentence: 'a person on a sidewalk jumping with an umbrella'. Find frequency of the letter 'a'

Output: 5


Input: Consider Input: Sentence: 'a man swinging a bat while playing baseball'. Find frequency of the letter 'm'

Output: 1


Input: Consider Input: Sentence: 'a blue tripocal bird is perched on a wooden fence'. Find frequency of the letter 'd'


Output: 3