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

Ex Input:
Sentence: 'a dog sitting in the back of a truck flat bed'. Find frequency of the letter 'h'

Ex Output:
1


Ex Input:
Sentence: 'a baseball player dropping his bat and starting to run'. Find frequency of the letter 'o'

Ex Output:
2


Ex Input:
Sentence: 'a man holding a skewer of meat with an open fire oven behind him'. Find frequency of the letter 'p'

Ex Output:

1