Crud Operations

Question

When inserting the error is showing like this   "'Conversion failed when converting the varchar value 'AP' to data type int.'"

This My Code  (And Error is showing at ExecuteNonQuery()); 

Please Help me

protected void btn1_Click(object sender, EventArgs e)
{
    string firsName = fn.Text;
    string lName = ln.Text;
    string DeptName = dept.SelectedItem.Text;
    string Gender = string.Empty;
    if (m.Checked == true)
    {
        Gender = m.Text;
    }
    else
    {
        Gender = f.Text;
    }
    string hobby = string.Empty;
    if (h1.Checked == true)
    {
        hobby = h1.Text;
    }
    if (h2.Checked == true)
    {
        hobby = hobby+h2.Text;
    }
    if (h3.Checked == true)
    {
        hobby =hobby+h3.Text;
    }
    if (h4.Checked == true)
    {
        hobby =hobby+h4.Text;
    }
    string Dnum = dno.SelectedItem.Text;
    string State = stat.SelectedItem.Text;
    string City = ct.SelectedItem.Text;
    con.Open();
    string query = "Insert into emp values('" + firsName + "','" + lName + "','" + DeptName + "','" + Gender + "','" + hobby + "','" + Dnum + "','" + State + "','" + City + "')";
    SqlCommand cmd = new SqlCommand(query, con);
    int i = cmd.ExecuteNonQuery();
    con.Close();
    if (i == 1)
    {
        FillGrid();
        Response.Write("Emp Added");    
    }
}