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

Input: Consider Input: Sentence: 'a woman walking on a shore next to a river'. Find frequency of the letter 'v'

Output: 1


Input: Consider Input: Sentence: 'a jet that is flying in the sky with a banner behind it'. Find frequency of the letter 'r'

Output: 1


Input: Consider Input: Sentence: 'some people are sitting out on lawn chairs'. Find frequency of the letter 'i'


Output: 3