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

Input: Consider Input: Sentence: 'a red and white train passing a train station'. Find frequency of the letter 'a'

Output: 7


Input: Consider Input: Sentence: 'a young elephant is touching a bigger elephant with its trunk'. Find frequency of the letter 'i'

Output: 5


Input: Consider Input: Sentence: 'three white wire park benches end to end on a sidewalk'. Find frequency of the letter 'k'


Output: 2