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 are riding on canoes down a river'. Find frequency of the letter 'e'

Output: 5


Input: Consider Input: Sentence: 'a train going over a bridge with some buildings in the background'. Find frequency of the letter 'd'

Output: 3


Input: Consider Input: Sentence: 'heavy traffic going and coming on a busy highway'. Find frequency of the letter 'f'


Output: 2