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

Input: Consider Input: Sentence: 'two people and two children walking in a building'. Find frequency of the letter 'd'

Output: 3


Input: Consider Input: Sentence: 'a bunch of green bananas is hanging on a tree'. Find frequency of the letter 'n'

Output: 7


Input: Consider Input: Sentence: 'the city bus is traveling down the road'. Find frequency of the letter 's'


Output: 2