Parentheses Problem

Time Limit: 1 sec

 

The Problem

Suppose I have n pair of parentheses, both starting and ending. The Staring one is “(“ and the ending is “)”.

 

Example:

If n = 2, I have two starting and two ending Parentheses. I can match parenthesis in two ways (()) and () ().

If n = 3, I can form these in 5 ways, those are ((())), () (()), () () (), (()) () and (() ()).

 

The Input

The input contains a number in every line n>0 denotes the number of pair of parenthesis. The input number is not greater than 20. Input is terminated by EOF.

 

The Output:

For each line of input, you have to print the number of expressions containing n pair of parentheses, which are correctly matched with the case number in a separate line.

 

Sample Input:

2

3

 

Sample Output:

Case 1: 2

Case 2: 5

 

 

 

[School Level]

Inter School & College Programming Contest (ISCPC) 2015 

Problem Setter: Parag Paul