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We have N persons sitting on a round table. Any person can do a handshake with any other person.

1

2 3

4

Handshake with 2-3 and 1-4 will cause cross.

In how many ways these N people can make handshakes so that no two handshakes cross each other. N would be even.

**Example 1:**

**Input:**
N = 2
**Output:**
1
**Explanation:**
{1,2} handshake is
possible.

**Example 2:**

**Input:**
N = 4
**Output:**
2
**Explanation:**
{{1, 2}, {3, 4}} are the
two handshakes possible.
{{1, 3}, {2, 4}} is another
set of handshakes possible.

**Your Task:**

You don't need to read input or print anything. Your task is to complete the function **count()** which takes an integer **N** as input parameters and returns an integer, the total number of handshakes possible so that no two handshakes cross each other.

**Expected Time Complexity:** O(2^{N})

**Expected Space Complexity:** O(1)

**Constraints:**

1 <= N <= 30

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Handshakes

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