Как я могу нажать 2-ю кнопку, когда button1 все еще работает

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       private void button1_Click(object sender, EventArgs e)
        {
            for (int i = 0; i < 1000000; i++)
            {
                label1.Text = i.ToString();
            }
           
        }

        private void button2_Click(object sender, EventArgs e)
        {
            label1.Text = 0.ToString();
        }</pre

After i press button1, i is increasing and button2 is Locked until i is finished.
how can i press button2 at anytime?

What I have tried:

<pre>      private void button1_Click(object sender, EventArgs e)
        {
            Thread th1 = new Thread(Increment);
            th1.Start();
           
        }
        private void Increment()
        {
            for (int i = 0; i < 10000; i++)
            {
                label1.Text = i.ToString();
            }
        }

        private void button2_Click(object sender, EventArgs e)
        {
            reset();
        }
        private void reset()
        {
            label1.Text = 0.ToString();
        }

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