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

Sentence: 'the large modern train is on the train track'. Find frequency of the letter 'm'
1

Sentence: 'a police officer who is riding on a horse'. Find frequency of the letter 'p'
1

Sentence: 'gloomy blue crowds are over a clock tower'. Find frequency of the letter 'o'

6