Self Exercise #12 CS311

#include <iostream>
using namespace std;
int mystery(int n);
//Precondition n > = 1.
int main()
{
 cout << mystery(3);
 return 0;
}
int mystery(int n)
{
 if (n <= 1)
 return 1;
 else
 return ( mystery(n - 1) + n );
}