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

Input: Consider Input: Sentence: 'a bunch of broken down trains sit in a yard'. Find frequency of the letter 'n'

Output: 5


Input: Consider Input: Sentence: 'there is a zebra that is walking enar a car'. Find frequency of the letter 'r'

Output: 4


Input: Consider Input: Sentence: 'a young woman leaning against a wall with her hands placed on her luggage'. Find frequency of the letter 'a'


Output: 10