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

Ex Input:
Sentence: 'two indian women in colorful garb standing barefoot with two indian men'. Find frequency of the letter 'd'

Ex Output:
3


Ex Input:
Sentence: 'the snowboarder wearing a dark helmet sprays snow into the air'. Find frequency of the letter 'w'

Ex Output:
3


Ex Input:
Sentence: 'a young man riding a skateboard into the air'. Find frequency of the letter 'g'

Ex Output:

2