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

Ex Input:
Sentence: 'vanity sitting atop a base with two doors and a mirror overhead'. Find frequency of the letter 'n'

Ex Output:
3


Ex Input:
Sentence: 'two giraffes, one standing and one laying down'. Find frequency of the letter 'g'

Ex Output:
3


Ex Input:
Sentence: 'an old house with a clock and statues'. Find frequency of the letter 'i'

Ex Output:

1