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

Input: Consider Input: Sentence: 'a toilet sits in a cluttered bathroom next to a sink'. Find frequency of the letter 'a'

Output: 4


Input: Consider Input: Sentence: 'a man standing on a tennis court holding a racquet'. Find frequency of the letter 's'

Output: 2


Input: Consider Input: Sentence: 'a girl with a backpack walks through a crowded street'. Find frequency of the letter 'a'


Output: 6