Problem Reading Datavalues To An Arraylist

I have an SQL command below that works fine

"SELECT sum(Preference) FROM [projectDB].[dbo].[Vote] group by preference;

SqlDataReader datareader = cmdPres.ExecuteReader();
ArrayList myArr = new ArrayList();



when i read the data in the values i get are
10,14,10,17

I want to loop through the reader, then add the values to an arrayList. Then i want to check of the value in the arrayList is greater than 15 but it dosent work. I get an error message when i add
sum(Prefernece) to the arraylist, it will not allow me.

while (dreader.Read())
{
myArr.Add(datareader["sum(Preference)"].ToString());

if(myArr.??? > 15)
{
Response.Write("Its greater than 15");
}
}