Message box in asp.net

using System.Diagnostics;
using System.Runtime.InteropServices;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
[DllImport("User32.dll")]
public static extern int MessageBox(int h, string m, string c, int type);
protected void MBox_Click(object sender, EventArgs e)
{
int ok = MessageBox(0, "API Message Box", "API Demo", 1);
MessageBox(0, ok.ToString(), "API Demo", 0);
}
}