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 riding a white surfboard on a large wave'. Find frequency of the letter 'a'

Output: 7


Input: Consider Input: Sentence: 'soccer players on opposite teams fight for control over a ball'. Find frequency of the letter 't'

Output: 4


Input: Consider Input: Sentence: 'a young asian guy carrying a suitcase and smiling'. Find frequency of the letter 'r'


Output: 2