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

Input: Consider Input: Sentence: 'a man sitting inside a green military truck talking to someone'. Find frequency of the letter 'i'

Output: 7


Input: Consider Input: Sentence: 'a couple of girls are hanging out at a restaurant'. Find frequency of the letter 'l'

Output: 2


Input: Consider Input: Sentence: 'the woman is swinging her tennis racket at the ball'. Find frequency of the letter 'o'


Output: 1