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

Ex Input:
Sentence: 'an image of a street sign with a corner restaurant'. Find frequency of the letter 'u'

Ex Output:
1


Ex Input:
Sentence: 'a kitchen with hanging lights, an island with sink and bar stools, a refrigerator, small pantry door, wooden cabinets and shiny wood floor'. Find frequency of the letter 'n'

Ex Output:
12


Ex Input:
Sentence: 'a woman sitting on top of a couch next to a cat'. Find frequency of the letter 'o'

Ex Output:

6