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

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: 'a glass vase sits between two statues'. Find frequency of the letter 'o'

Ex Output:
1


Ex Input:
Sentence: 'sandwich sitting on counter table in a restaurant'. Find frequency of the letter 'a'

Ex Output:

5