find any invalid character in the PATH environment variable

FindInvalidCharacterInEnvironment.cs

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


namespace FindInvalidCharacterInEnvironment
{
    class Program
    {
        static void Main(string[] args)
        {
            var invalidCharacter= new HashSet<char>{
                '\"', '<', '>', '|', '\0',
                (char)1, (char)2, (char)3, (char)4, (char)5, (char)6, (char)7, (char)8, (char)9, (char)10,
                (char)11, (char)12, (char)13, (char)14, (char)15, (char)16, (char)17, (char)18, (char)19, (char)20,
                (char)21, (char)22, (char)23, (char)24, (char)25, (char)26, (char)27, (char)28, (char)29, (char)30,
                (char)31
                
            };
            var r = Environment.GetEnvironmentVariable("PATH").Split(';').Where(s=> s.Any(c=> invalidCharacter.Contains(c))).First();
            Console.WriteLine(r);
            Console.WriteLine(BitConverter.ToString(Encoding.Unicode.GetBytes(r)).Replace("-"," "));
        }
    }
}