xpath question

I can get the webpage with HttpWebRequest now i am trying to write corret xpath code for this 

there is 81 options but i copy poste 8 of them i am trying to get all of them

here is my code

for (int i = 1; i < 82; i++)
                    {
                        ab = htmlDocument.DocumentNode.SelectSingleNode("//select[@name='gradovi']/option[" + i.ToString() + "]").InnerText.Trim();
                        MessageBox.Show(ab);
                        cities.Items.Add(ab);

                    }

here is html

<select name="gradovi" onchange='this.form.submit()'><option value="1">Banovići</option><option value="2">Banja Luka</option><option value="3">Bihać</option><option value="4">Bijeljina</option><option value="5">Bileća</option><option value="6">Bos.Brod</option><option value="7">Bos.Dubica</option><option value="8">Bos.Gradiška</option>

any help? thank you

best regards cihad yıldız