Use C++

There are n people in a room, where n is an integer greater than or equal to 2. Each person shakes hands once with every other person. What is the total number of handshakes in the room? Write a recursive function to solve this problem, with the following header: int handshake (int n) where handshake(n) returns the total number of handshakes for n people in the room. To get you started, if there are only two people in the room, then handshake(2) = 1