using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Runtime.InteropServices;

namespace calculate

{

    struct StdHandleEnum

    {

        public const int STD_INPUT_HANDLE = -10;

        public const int STD_OUTPUT_HANDLE = -11;

        public const int STD_ERROR_HANDLE = -12;

    };

    static class ConsoleEx

    {

        internal struct COORD

        {

            public short X;

            public short Y;

        }

        [StructLayout(LayoutKind.Sequential, Pack = 1)]

        internal struct CONSOLE_SCREEN_BUFFER_INFO

        {

            public COORD Size;

            public COORD p1;

            public short a1;

            public short w1;

            public short w2;

            public short w3;

            public short w4;

            public COORD m1;

        }

        [DllImport("kernel32.dll")]

        public static extern int GetStdHandle(int nStdHandle);

        [DllImport("kernel32.dll")]

        public static extern bool GetConsoleScreenBufferInfo(int hConsoleOutput, out CONSOLE_SCREEN_BUFFER_INFO lpConsoleScreenBufferInfo);

        [DllImport("kernel32.dll")]

        public static extern bool SetConsoleCursorPosition(int hConsoleOutput, COORD dwCursorPosition);

        [DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]

        public static extern bool FillConsoleOutputCharacter(int hConsoleOutput, short cCharacter, int nLength, COORD WriteCoord, out int lpNumberOfCharsWritten);

        public static void Clear()

        {

            CONSOLE_SCREEN_BUFFER_INFO CSBI;

            int hOut;

            int CharOut;

            COORD Home;

            hOut = GetStdHandle(StdHandleEnum.STD_OUTPUT_HANDLE);

            GetConsoleScreenBufferInfo(hOut, out CSBI);

            Home.X = 0;

            Home.Y = 0;

            FillConsoleOutputCharacter(hOut, (short)' ', CSBI.Size.X * CSBI.Size.Y, Home, out CharOut);

            SetConsoleCursorPosition(hOut, Home);

        }

    }

}