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

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button2_Click(object sender, EventArgs e)
        {

            for (int i = 5; i >= 0; i--)
            {
                if ((listBox1.Items[i].ToString() == "a") || (listBox1.Items[i].ToString() == "e"))
                {
                    listBox1.Items.Remove(listBox1.Items[i]);
                }
            }
        }

        private void button1_Click(object sender, EventArgs e)
        {
            listBox1.Items.Clear();
            listBox1.Items.Add("a");
            listBox1.Items.Add("b");
            listBox1.Items.Add("c");
            listBox1.Items.Add("d");
            listBox1.Items.Add("e");
            listBox1.Items.Add("f");
        }
    }
}