public class Summation {

	// Main method.
	public static void main(String[] args) {
		for (String s: args) {
			try {
				int n = Integer.parseInt(s);
				int x = fibonacci(n);
				System.out.println(x);
			}
			catch(NumberFormatException e) {
				System.out.println("The input is not a number.");
			}            
        }
	}
	
	// Summation from 0 to N
	public static int sum(int n) {
		int x = 0;
		
		for(int i = 0;i <= n;i++) {
			x = x + i;	
		}
		
		return x;
	}
	
	// Recursive function for finding the Nth Fibonacci number.
	public static int fibonacci(int n) {
		int x = 0;
		
		if (n == 0) {
			x = 0; 
		}
		else if (n == 1) {
			x = 1;
		}
		else {
			x = fibonacci((n-1)) + fibonacci((n-2));
		}
		
		return x;			
	}
	
}