In this task, you need to count the number of times the given letter appears in the given sentence.

Sentence: 'a dog sitting in the back of a truck flat bed'. Find frequency of the letter 'h'
1

Sentence: 'one man grabbing another at a table while laughing'. Find frequency of the letter 'n'
5

Sentence: 'a crowd of people riding on top of snow covered ground'. Find frequency of the letter 'o'

9