<select class="form-control" id="p_in_qty" style="width:100px; margin-left:50px;">
   <?php
   $array = array(1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30);
              foreach ($array as $value) {
                       echo '<option value="'.$value.'">'.$value.'</option>';
                 }
 ?>
  </select>




<select class="form-control" id="p_av_qty" style="width:100px; margin-left:50px;">
   <?php
   $array = array(1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30);
              foreach ($array as $value) {
                       echo '<option value="'.$value.'">'.$value.'</option>';
                 }
 ?>
  </select>



 <button type="button"  onClick="check();" class="btn btn-primary btn-md">Check</button>

function check(){

         var i_qty = $('#p_in_qty').val();
         var s_qty = $('#p_av_qty').val();

         if(s_qty > i_qty){


        alert("s_qty is greater than i_qty") ;

    }else{
       alert("fine");
      }

    }