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

Sentence: 'a close up of a bird on the outside window sill'. Find frequency of the letter 'c'
1

Sentence: 'a couple of people that are on a baseball field'. Find frequency of the letter 'c'
1

Sentence: 'a white small dog lying on a shoe'. Find frequency of the letter 'o'

3