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: 'a microwave oven with a yellow note on the door'. Find frequency of the letter 'w'

Ex Output:
3


Ex Input:
Sentence: 'a guy preforming a skateboard trick at a skate park'. Find frequency of the letter 'm'

Ex Output:

1