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

Ex Input:
Sentence: 'a child sitting a table with a pizza in front of him'. Find frequency of the letter 'h'

Ex Output:
3


Ex Input:
Sentence: 'supplies and tools are arranged on the floor with a hard hat and bag'. Find frequency of the letter 'n'

Ex Output:
4


Ex Input:
Sentence: 'a salad with some strawberries on a plate with a fork and drink'. Find frequency of the letter 'r'

Ex Output:

5