using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace CalculateSum
{
	public partial class MainForm : Form
	{
		public MainForm()
		{
			InitializeComponent();
		}

		private void m_btnCalculate_Click(object sender, EventArgs e)
		{
			try
			{
				Cursor.Current = Cursors.WaitCursor;
				m_btnCalculate.Enabled = false;

				int target = Int32.Parse(m_txtTarget.Text);
				int sum = 0;
				for(int i = 1; i <= target; i++)
					sum += i;
				MessageBox.Show(
					String.Format("Result: {0}.", sum),
					"Finished",
					MessageBoxButtons.OK,
					MessageBoxIcon.Asterisk,
					MessageBoxDefaultButton.Button1);
			}
			catch(Exception ex)
			{
				MessageBox.Show(
					String.Format("Some error occurs. Details: {0}.", ex.Message),
					"Error",
					MessageBoxButtons.OK,
					MessageBoxIcon.Asterisk,
					MessageBoxDefaultButton.Button1);
			}
			finally
			{
				Cursor.Current = Cursors.Default;
				m_btnCalculate.Enabled = true;
			}
		}
	}
}