help needed with menu using jquery

help needed with menu using jquery

<!DOCTYPE html>
<html>
<head>
  <style>
p { background:#dad;
font-weight:bold;
font-size:16px; }

.mn_offLeft {
    display:none;
}
</style>
  <script src="http://code.jquery.com/jquery-latest.min.js"></script>
<script type="text/javascript">
jQuery(document).ready(function($){
$(".a1 a").click(function () {
    $("#c1").show();
    $("#c2").hide();
    $("#c3").hide();
    });
$(".a2 a").click(function () {
    $("#c2").show();
    $("#c1").hide();
    $("#c3").hide();
    });
$(".a3 a").click(function () {
    $("#c3").show();
    $("#c1").hide();
    $("#c2").hide();
    });
});
</script>
</head>
<body>
    <button>Toggle 'em</button>

<p>Hiya</p>
<p>Such interesting text, eh?</p>


                          <ul class="shadeTabs" id="mainTab">
                          <li><span class="a1"><a href="#">Page 1</a></span></li>
                          <li><span class="a2"><a href="#">Page 2</a></span></li>
                          <li><span class="a3"><a href="#">Page 3</a></span></li>
                          </ul>
                         
                           <div id="c1">Hello1</div>
                           <div id="c2">Hello2</div>
                           <div id="c3">Hello3</div>
</body>
</html>

this is my code....as u can see the jquery code is repeating itself hw to avoid this, i am new to jquery any help is deeply appreciated