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

Ex Input:
Sentence: 'the wooden kitchen has a small child's plastic table in it'. Find frequency of the letter 'n'

Ex Output:
3


Ex Input:
Sentence: 'an empty clean kitchen with island, marble countertops , stove and cabinetry'. Find frequency of the letter 'l'

Ex Output:
3


Ex Input:
Sentence: 'a group of peopl standing arond on the beach wearing wetsuits'. Find frequency of the letter 'f'

Ex Output:

1