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

Input: Consider Input: Sentence: 'a man opening up a package sitting on a couch'. Find frequency of the letter 'n'

Output: 5


Input: Consider Input: Sentence: 'a large motorcycle that has a man dressed in old clothing next to it'. Find frequency of the letter 'a'

Output: 6


Input: Consider Input: Sentence: 'an audience watches as a bird spreads its wings'. Find frequency of the letter 'd'


Output: 3