using System;
using Microsoft.CSharp;
using System.Collections.Generic;
using System.CodeDom.Compiler;
using System.Diagnostics;

class Program
{
    static void Main(string[] args)
    {
        string sourceCode = "class e{static void Main(){System.Console.Write(new char[1\n#if l\n#else\n*5]{'w','o','r','l','d'\n#if o\n#else\n});\n#endif\n}\n#endif\n}";

        Console.WriteLine(isPristine(sourceCode) ? "Pristine" : "Not pristine");
        Console.ReadLine();
    }

    static bool isPristine(string sourceCode)
    {
        using (var csc = new CSharpCodeProvider(new Dictionary<string, string>() { { "CompilerVersion", "v3.5" } }))
        {
            var parameters = new CompilerParameters(new[] { "mscorlib.dll", "System.Core.dll" });

            int length = sourceCode.Length;
            List<string> substringsThatWork = new List<string>();

            for (int i = 0; i < length; i++)
            {
                for (int j = 1; j < length - i; j++)
                {
                    string sourceWithRemoval = sourceCode.Remove(i, j);
                    CompilerResults results = csc.CompileAssemblyFromSource(parameters, sourceWithRemoval);

                    if (results.Errors.Count == 0)
                    {
                        Debug.WriteLine("Still works by removing:");
                        Debug.WriteLine("@{0}@ ", sourceWithRemoval);
                        Debug.WriteLine("At index {0}.", i);

                        return false;
                    }
                }
            }
        }

        return true;
    }
}