using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(NthFib(10));

    }

    public static int NthFib(int n)

    {

        //Fibonacci series

        //0,1,1,2,3,5,8,13,21

        int a = 0;

        int c = 0;

        int b = 1;

        if(n == 0)

            return 0;

        for(int i = 2; i < n; i++)

        {

            c = a + b;

            a = b;

            b = c;

        }

        return b;

    }

}