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

Ex Input:
Sentence: 'a long row of tables displaying lots of fruit'. Find frequency of the letter 'o'

Ex Output:
5


Ex Input:
Sentence: 'a person on a sidewalk jumping with an umbrella'. Find frequency of the letter 'a'

Ex Output:
5


Ex Input:
Sentence: 'the two giraffes walk in the heavily weeded area'. Find frequency of the letter 'f'

Ex Output:

2