rand_&_parse

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            Random rand = new Random();
            textBox1.Text = rand.Next(2, 20).ToString();
            textBox2.Text = rand.Next(4, 40).ToString();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            int a = Int32.Parse(textBox1.Text);
            int b = Int32.Parse(textBox2.Text);
            int c = a + b;
            label1.Text = c.ToString();
        }

    }
}