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

Ex Input:
Sentence: 'an elephant has taken a man's hat in its trunk'. Find frequency of the letter 'p'

Ex Output:
1


Ex Input:
Sentence: 'a man hits a tennis ball with a racket on the court'. Find frequency of the letter 'c'

Ex Output:
2


Ex Input:
Sentence: 'a pizza restaurant that is below another business'. Find frequency of the letter 'o'

Ex Output:

2