private void button1_Click(object sender, EventArgs e)
        {
            var income = decimal.Parse(textBox1.Text);

            if ( income > 0 && income < 9999 )
            {
                income = income + 77;
                customLabel.Text = income.ToString();
            }
            else if (income >= 10000 && income <= 99999)
            {
                income = income * 3;
                customLabel.Text = income.ToString();
            }

        }