instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'a doorway looking into a small bathroom with white toilet'. Find frequency of the letter 'r'
answer:
2


question:
Sentence: 'a red fire hydrant opened and spilling water'. Find frequency of the letter 'd'
answer:
4


question:
Sentence: 'a male skateboarder skateboards on a wall in an enclosed area'. Find frequency of the letter 'a'
answer:

11