instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'a mixed bouquet of flowers in a glass vase set before a window'. Find frequency of the letter 'w'
answer:
3


question:
Sentence: 'a red and white train passing a train station'. Find frequency of the letter 'a'
answer:
7


question:
Sentence: 'a baseball player from the mariners walks out to his place on the field'. Find frequency of the letter 'm'
answer:

2