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

Ex Input:
Sentence: 'a metallic stove top oven inside of a wooden kitchen'. Find frequency of the letter 'v'

Ex Output:
2


Ex Input:
Sentence: 'man in a sleeping bag on the floor using a laptop computer'. Find frequency of the letter 'i'

Ex Output:
3


Ex Input:
Sentence: 'a camera and flash setup to take a pic of the inside of a oven'. Find frequency of the letter 'e'

Ex Output:

6


