using System;

using System.Collections.Generic;

using System.Security.Cryptography;

using System.Text;

​

public class Program

{

    public static void Main()

    {

        string[] listCaselle = 

        {

             "a1"

            ,"aa2"

            ,"aaa3"              

            ,"System.Collections.GenericSystem.Collections.GenericSystem.Collections.GenericSystem.Collections.GenericSystem.Collections.Generic"

            ,"System.Collections.GenericSystem.Collections.GenericSystem.Collections.GenericSystem.Collections.GenericSystem.Collections.Generic"

            ,"System.Collections.GenericSystem.Collections.GenericSystem.Collections.GenericSystem.Collections.GenericSystem.Collections.Generic"

        };

​

        var patternSplit = ", ";

        var patternResult = "{0} e altri {1}";

        StringBuilder sb = new StringBuilder();

        int c= 0;

        for(c = 0; c < listCaselle.Length ; c++)

        {

            if(sb.Length + listCaselle[c].Length <= 255 )           

                sb.AppendFormat("{0}{1}", listCaselle[c], patternSplit);

            else 

            {               

                sb.Remove(sb.Length - patternSplit.Length , patternSplit.Length );

                break;

            }                           

        }

        int left = listCaselle.Length - c;

        if(left > 0)

            Console.WriteLine(string.Format(patternResult, sb.ToString(),left));

        else

            Console.WriteLine(sb.ToString());

​

    }

}