private void numericUpDown_ValueChanged(object sender, EventArgs e)
        {
            if (numericUpDown_start_A.Value > numericUpDown_end_A.Value)
            {
                numericUpDown_end_A.Minimum = numericUpDown_start_A.Value;
            }
            else
            {
                if (numericUpDown_end_A.Value > numericUpDown_start_A.Value)
                {
                    numericUpDown_end_B.Minimum = numericUpDown_start_B.Value;
                }
                else
                {
                    if (numericUpDown_end_B.Value > numericUpDown_start_B.Value)
                    {
                        numericUpDown_end_C.Minimum = numericUpDown_start_C.Value;
                    }
                    else
                    {
                        if (numericUpDown_end_C.Value == numericUpDown_start_C.Value)
                        {
                            numericUpDown_end_D.Minimum = numericUpDown_start_D.Value;

                        }
                    }

                }


            }
        }