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

Ex Input:
Sentence: 'several zebras  and a giraffe in an enclosure'. Find frequency of the letter 's'

Ex Output:
3


Ex Input:
Sentence: 'a blue bowl holding mashed bananas and oatmeal with a bottle of sugar and cinnamon sitting beside it'. Find frequency of the letter 'g'

Ex Output:
3


Ex Input:
Sentence: 'people watching a woman play a video game'. Find frequency of the letter 'o'

Ex Output:

3