instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'a person riding a surfboard in the middle of a wave'. Find frequency of the letter 'o'
answer:
3


question:
Sentence: 'a woman sitting in front of a giant slice of cheese pizza'. Find frequency of the letter 'e'
answer:
4


question:
Sentence: 'a herd of horses standing next to each other on a field'. Find frequency of the letter 'r'
answer:

3