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

Ex Input:
Sentence: 'a man in a suit makes the first slice into a cake'. Find frequency of the letter 't'

Ex Output:
4


Ex Input:
Sentence: 'a scene at night; a plane alone on a runway with lit-up city buildings on the horizon'. Find frequency of the letter 'w'

Ex Output:
2


Ex Input:
Sentence: 'an old man petting a black and white cow'. Find frequency of the letter 'k'

Ex Output:

1