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

Input: Consider Input: Sentence: 'some people sitting on surfboards in the water'. Find frequency of the letter 't'

Output: 4


Input: Consider Input: Sentence: 'a little boy that has a toothbrush in his mouth'. Find frequency of the letter 'r'

Output: 1


Input: Consider Input: Sentence: 'a wall with exposed insulation and tools on the floor'. Find frequency of the letter 'e'


Output: 3