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

Ex Input:
Sentence: 'two young ladies that are dancing in the room together'. Find frequency of the letter 'a'

Ex Output:
4


Ex Input:
Sentence: 'a bird is perched on a container in a person's hand'. Find frequency of the letter 'c'

Ex Output:
2


Ex Input:
Sentence: 'two giraffes with their heads side by side'. Find frequency of the letter 'y'

Ex Output:

1