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

Input: Consider Input: Sentence: 'young girl playing with refrigerator magnet while kneeling on floor'. Find frequency of the letter 'n'

Output: 6


Input: Consider Input: Sentence: 'a person on a skateboard going down a ramp'. Find frequency of the letter 'n'

Output: 4


Input: Consider Input: Sentence: 'a person is skiing on the slopes snow bank'. Find frequency of the letter 'o'


Output: 4