code for following program

using System;
using System.Collections.Generic;
using System.Text;

namespace fibseries
{

class Program
    {
        static void Main(string[] args)
        {
            int num;
            Console.WriteLine("Please Enter a number:");
             num = Convert.ToInt32(Console.ReadLine());
             Console.WriteLine("\n");
             Console.WriteLine("The first " + num + " number(s) in the fibonacci series are: ");
             FibonacciSeries(num);
             Console.Read();
        }
        // Fibonacci Code
        public static int FibonacciSeries(int n)
        {
             int previous = -1;
             int next = 1;
             for (int i = 0; i < n; i++)
             {
                 int sum = next + previous;
                 previous = next;
                 next = sum;
                 Console.WriteLine(next);
             }
             return next;
         }

    }