c# listview 导入txt 添序号

c# listview 导入txt 加序号

我有一段数据

123-123

456-456

789-789

用openfiledialog导入listview，需要分割，

然后在前面加一栏序号，怎么实现啊

如图：

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

namespace WindowsFormsApplication22
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            int couns=0;
            listView1.View = View.Details;
            ColumnHeader ch1 = new ColumnHeader();
            ch1.Text = "序号";
            ColumnHeader ch2=new ColumnHeader();
            ch2.Text = "账号";
            ColumnHeader ch3=new ColumnHeader();
            ch3.Text = "密码";
            listView1.Columns.Add(ch1);
            listView1.Columns.Add(ch2);
            listView1.Columns.Add(ch3);
            OpenFileDialog file = new OpenFileDialog();
            if (file.ShowDialog() == DialogResult.OK) {
                FileStream fs=new FileStream(file.FileName,FileMode.Open);
                StreamReader sr = new StreamReader(fs);
                sr.BaseStream.Seek(0, SeekOrigin.Begin);
                while (!sr.EndOfStream) {       
                    string[] ss = sr.ReadLine().Split(new char[] { '-' }, StringSplitOptions.RemoveEmptyEntries); 
 
                    if (ss.Length == 2)
                    {
                        couns++;
                        string[] sss = new string[3] { couns.ToString(), ss[0], ss[1] };
                        ListViewItem lvi = new ListViewItem(sss);
                        listView1.Items.Add(lvi);
                    }
                }
            }
        }
    }
}