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

Ex Input:
Sentence: 'man sitting on the side of a van playing the guitar'. Find frequency of the letter 'm'

Ex Output:
1


Ex Input:
Sentence: 'hand holding a white calculator inside a store'. Find frequency of the letter 'o'

Ex Output:
3


Ex Input:
Sentence: 'many fresh vegetables have been placed near together'. Find frequency of the letter 'a'

Ex Output:

5