/* package whatever; // don't place package name! */

/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		int n = 10;
		System.out.println(fib(10));
	}

	private static int fib(int n){
		if(n==0) return 0;
		 
		return n+fib(n-1);
	}
}