I want to select a letter and it gives me the number of that letter.

<select name="day" id="day">
<option value='1'>1</option><option value='2'>2</option><option value='3'>3</option><option value='4'>4</option><option value='5'>5</option><option value='6'>6</option><option value='7'>7</option><option value='8'>8</option><option value='9'>9</option><option value='10'>10</option><option value='11'>11</option><option value='12'>12</option><option value='13'>13</option><option value='14'>14</option><option value='15'>15</option><option value='16'>16</option><option value='17'>17</option><option value='18'>18</option><option value='19'>19</option><option value='20'>20</option><option value='21'>21</option><option value='22'>22</option><option value='23'>23</option><option value='24'>24</option><option value='25'>25</option><option value='26'>26</option></select>


<select name="year" id="year">
<option value='a'>a</option><option value='b'>b</option><option value='c'>c</option><option value='d' selected>d</option><option value='e'>e</option><option value='f'>f</option><option value='g'>g</option><option value='h'>h</option><option value='i'>i</option><option value='j'>j</option><option value='k'>k</option><option value='l'>l</option><option value='m'>m</option><option value='n'>n</option><option value='o'>o</option><option value='p'>p</option><option value='q'>q</option><option value='r'>r</option><option value='s'>s</option><option value='t'>t</option><option value='u'>u</option><option value='v'>v</option><option value='w'>w</option><option value='x'>x</option><option value='y'>y</option><option value='z'>z</option></select>