Sudoku.Form1.congratulations C# (CSharp) Method

        public void congratulations()
        {
            if (textBox1.Text != "" && textBox2.Text != "" && textBox3.Text != "" && textBox4.Text != "" &&
                textBox5.Text != "" && textBox6.Text != "" && textBox7.Text != "" && textBox8.Text != "" &&
                textBox9.Text != "" && textBox10.Text != "" && textBox11.Text != "" && textBox12.Text != "" &&
                textBox13.Text != "" && textBox14.Text != "" && textBox15.Text != "" && textBox16.Text != "")
            {

                if (textBox1.BackColor != Color.Red && textBox2.BackColor != Color.Red && textBox3.BackColor != Color.Red && textBox4.BackColor != Color.Red &&
            textBox5.BackColor != Color.Red && textBox6.BackColor != Color.Red && textBox7.BackColor != Color.Red && textBox8.BackColor != Color.Red &&
            textBox9.BackColor != Color.Red && textBox10.BackColor != Color.Red && textBox11.BackColor != Color.Red && textBox12.BackColor != Color.Red &&
            textBox13.BackColor != Color.Red && textBox14.BackColor != Color.Red && textBox15.BackColor != Color.Red && textBox16.BackColor != Color.Red)
                {
                    label1.Visible = true;
                }

            }
            else {

                label1.Visible = false;
            }
        }