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

Ex Input:
Sentence: 'a few men walking through a market place'. Find frequency of the letter 'f'

Ex Output:
1


Ex Input:
Sentence: 'a person is performing a stunt on a snowboard'. Find frequency of the letter 'p'

Ex Output:
2


Ex Input:
Sentence: 'a girl in a blue shirt is a soccer goalie'. Find frequency of the letter 'b'

Ex Output:

1