using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;

namespace CsWindowsDirectory
{
    class Program
    {
        [DllImport("kernel32", CharSet = CharSet.Auto)]
        private static extern uint GetWindowsDirectory(string buffer, uint length);

        //Windowsディレクトリを取得する
        public static string GetWindowsDirectoryPath()
        {
            string buf = new string(' ', 260);
            uint len = GetWindowsDirectory(buf, 260);
            return buf.Substring(0, (int)len);
        }

        static void Main(string[] args)
        {
            Console.WriteLine(GetWindowsDirectoryPath());
        }
    }
}