Windows Forms: Timer control in C#

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

namespace TimerControl
{
    public partial class Form1 : Form
    {
        int value;
        public Form1()
        {
            InitializeComponent();
        }

        private void timer1_Tick(object sender, EventArgs e)
        {
            //Update textbox
            txtValue.Text = (value++).ToString();
        }

        private void btnStart_Click(object sender, EventArgs e)
        {
            if(int.TryParse(txtValue.Text, out value))
            {
                timer1.Start();
            }
        }

        private void btnStop_Click(object sender, EventArgs e)
        {
            timer1.Stop();
        }
    }
}