Program that computes Fibonacci iteratively [C#]

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

namespace fibonacciseries
{
    class Program
    {
        static void Main()
        { char ch;
        do
        {
            Console.Clear();
            Console.WriteLine("Enter the number to be fibonacci_series: " + "\n");

            int num = Convert.ToInt32(Console.ReadLine());
            int first = -1;
            int next = 1;
            int result = 0;
            int i;
            Console.WriteLine("Series Are :  " + "\n");
            for (i = 0; i < num; i++)
            {

                result = first + next;
                first = next;
                next = result;
                Console.WriteLine("\n" + result);
            }
                      
            Console.WriteLine("To continue Press (y)");
            ch = Convert.ToChar(Console.ReadLine());
           
        }
       
        while (ch =='y');
        }
    }
}