instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'a black computer with a screen reading "press any key to begin."'. Find frequency of the letter 'a'
answer:
5


question:
Sentence: 'an elephant has taken a man's hat in its trunk'. Find frequency of the letter 'p'
answer:
1


question:
Sentence: 'a dog is sitting on the couch watching tv'. Find frequency of the letter 'n'
answer:

3