C# Program to group the sequence of number

Combine Sequence Number.cs

using System;
using System.Collections.Generic;

namespace CombineSequenceNumbers
{
    class Program
    {
        static void Main(string[] args)
        {
            string input;

            // Getting intput
            Console.WriteLine("Enter the number: ");
            input = Console.ReadLine();

            // Calling the method
            Console.WriteLine(CombineSequenceNumber(input + ",0"));
            Console.ReadKey();
        }

        // Method to combine the seq number
        public static string CombineSequenceNumber(string ip)
        {
            string[] input = ip.Split(',');
            List<string> output = new List<string>();
            int startSeq = 0;
            for (int i = 0; i < input.Length-1; i++)
            {                
                if (startSeq == 0)
                    startSeq = Convert.ToInt32(input[i]);

                int curVal = Convert.ToInt32(input[i]);
                int nextVal = Convert.ToInt32(input[i+1]);

                if ( curVal + 1  != nextVal)
                {
                    if(startSeq == curVal)
                        output.Add(input[i]);
                    else
                        output.Add(startSeq + "-" + input[i]);
                    startSeq = 0;
                }
                
            }

            // returning the output
            return String.Join(",", output);
        }
    }
}