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

Ex Input:
Sentence: 'a woman standing in front of a bathroom sink in front of a mirror'. Find frequency of the letter 'o'

Ex Output:
8


Ex Input:
Sentence: 'salad and vegetables with me on top of plate'. Find frequency of the letter 'o'

Ex Output:
3


Ex Input:
Sentence: 'a stop sign behind a wall and palm tree'. Find frequency of the letter 'm'

Ex Output:

1