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

Input: Consider Input: Sentence: 'an area that has surrounded by a metal fence'. Find frequency of the letter 'o'

Output: 1


Input: Consider Input: Sentence: 'a person working at an airport, outside of an airplane'. Find frequency of the letter 'r'

Output: 5


Input: Consider Input: Sentence: 'a women who is walking in the snow in snow skis'. Find frequency of the letter 'n'


Output: 6