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

Ex Input:
Sentence: 'a ready to eat pizza on a rack'. Find frequency of the letter 'r'

Ex Output:
2


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 cat is sitting on a bench near the grass'. Find frequency of the letter 'h'

Ex Output:

2