[C#] Instruction Set

using System;
using System.Collections.Generic;

class InstructionSet_broken
{
    static void Main()
    {
        List < long > result = new List<long>();
        string opCode = "";
        do
        {
            opCode = Console.ReadLine();
            string[] codeArgs = opCode.Split(' ');


            switch (codeArgs[0])
            {
                case "INC":
                    {
                        int operandOne = int.Parse(codeArgs[1]);
                        operandOne++;
                        result.Add(operandOne);
                        break;
                    }
                case "DEC":
                    {
                        int operandOne = int.Parse(codeArgs[1]);
                        operandOne--;
                        result.Add(operandOne);
                        break;
                    }
                case "ADD":
                    {
                        long operandOne = long.Parse(codeArgs[1]);
                        long operandTwo = long.Parse(codeArgs[2]);
                        result.Add(operandOne+ operandTwo);
                        break;
                    }
                case "MLA":
                    {
                        long operandOne = long.Parse(codeArgs[1]);
                        long operandTwo = long.Parse(codeArgs[2]);
                        result.Add(operandOne*operandTwo);
                        break;
                    }

            }
        } while (opCode != "END");
        foreach (var item in result)
        {
            Console.WriteLine(item);
        }

    }
}