1833: Hands Shaking

Consider a meeting of n businessmen sitting around a circular table. To start the meeting, they must shake hands. Each businessman shakes the hand of exactly one other businessman. All handshakes happen simultaneously. We say that the shake is perfect if no arms cross each other. Given an int n, return the number of perfect shakes that exist for n businessmen.

Each case is a line containing a number n.n will be between 2 and 50,inclusive and n is even.

please output the number of perfect shakes that exist fot n businessmen perline.

2
4
8

1
2
14