instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'a traffic signal by a wire filled with some birds'. Find frequency of the letter 'e'
answer:
3

question:
Sentence: 'a man hitting a tennis ball with a tennis racquet'. Find frequency of the letter 't'
answer:
6

question:
Sentence: 'a man sitting next to a brown cow on a bench'. Find frequency of the letter 's'
answer:
1