instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'a guy surfs a wave with his surfboard'. Find frequency of the letter 's'
answer:
4

question:
Sentence: 'a group of people walking down a rain soaked street with umbrellas'. Find frequency of the letter 'w'
answer:
3

question:
Sentence: 'three woman preparing food on a kitchen counter'. Find frequency of the letter 'r'
answer:
4