const int INPUT_MOUSE = 0;
        const int INPUT_KEYBOARD = 1;
        const int INPUT_HARDWARE = 2;
        const uint KEYEVENTF_EXTENDEDKEY = 0x0001;
        const uint KEYEVENTF_KEYUP = 0x0002;
        const uint KEYEVENTF_UNICODE = 0x0004;
        const uint KEYEVENTF_SCANCODE = 0x0008;

        struct INPUT
        {
            public int type;
            public InputUnion u;
        }

        [StructLayout(LayoutKind.Explicit)]
        struct InputUnion
        {
            [FieldOffset(0)]
            public MOUSEINPUT mi;
            [FieldOffset(0)]
            public KEYBDINPUT ki;
            [FieldOffset(0)]
            public HARDWAREINPUT hi;
        }

        [StructLayout(LayoutKind.Sequential)]
        struct MOUSEINPUT
        {
            public int dx;
            public int dy;
            public uint mouseData;
            public uint dwFlags;
            public uint time;
            public IntPtr dwExtraInfo;
        }

        [StructLayout(LayoutKind.Sequential)]
        struct KEYBDINPUT
        {
            /*Virtual Key code.  Must be from 1-254.  If the dwFlags member specifies KEYEVENTF_UNICODE, wVk must be 0.*/
            public ushort wVk;
            /*A hardware scan code for the key. If dwFlags specifies KEYEVENTF_UNICODE, wScan specifies a Unicode character which is to 	                        be sent to the foreground application.*/
            public ushort wScan;
            /*Specifies various aspects of a keystroke.  See the KEYEVENTF_ constants for more information.*/
            public uint dwFlags;
            /*The time stamp for the event, in milliseconds. If this parameter is zero, the system will provide its own time stamp.*/
            public uint time;
            /*An additional value associated with the keystroke. Use the GetMessageExtraInfo function to obtain this information.*/
            public IntPtr dwExtraInfo;
        }

        [StructLayout(LayoutKind.Sequential)]
        struct HARDWAREINPUT
        {
            public uint uMsg;
            public ushort wParamL;
            public ushort wParamH;
        }