using of if else conditions inside for loop to change buttons(color) inside the jstl tags

Question

I have a serious question folks! I am trying to develop a JSP view and I am using 1) for and 2) if/else conditions, to change the colors of the buttons accordingly to green(if even i.e., if(i%2==0)) and red vice versa(if odd condn.,). But I am unable to achieve that for some reasons.If anybody could help me with that it would be of great help!

 <ul class="navigation"> 
 <% for(int i=0; i<31; i++) {%>
   <c:if test="${i % 2 == 0}">
   <li>
    <a  href="#" class="button green">
    <div class="id">PatientID:</div>
    <div class="name">Name:</div>
    <div class="info-number">Bed No:</div>
    </a> 
   </li>
  </c:if>
  <c:if test="${i % 2 != 0}">
   <li>
    <a href="#" class="button red">
    <div class="id">PatientID:</div>
    <div class="name">Name:</div>
    <div class="info-number">Bed No:</div>
    </a>
   </li>
  </c:if>
  <% } %>
  </ul>