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

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

        private void button1_Click(object sender, EventArgs e)
        {
            if (textBox1.Text != "" && textBox2.Text != "")
            {
                BigInteger num1 = new BigInteger(textBox1.Text);
                BigInteger num2 = new BigInteger(textBox2.Text);
                BigInteger num3 = num1.add(num2);
                label2.Text = num3.ToString();
                textBox1.Text = "";
                textBox2.Text = "";
            }

        }
        private void KeyPress(object sender, KeyPressEventArgs e)
        {
            if (!(char.IsDigit(e.KeyChar) || e.KeyChar == (char)Keys.Delete || e.KeyChar == (char)Keys.Back || e.KeyChar == '-' ||
                ((Control.ModifierKeys & Keys.Control) == Keys.Control)))
            {
                e.Handled = true;
                System.Media.SystemSounds.Beep.Play();
            }
        }

        private void richTextBox1_KeyPress(object sender, KeyPressEventArgs e)
        {
            e.Handled = true;
            System.Media.SystemSounds.Beep.Play();
        }
    }
}