Perform angularjs operation inside value attribute of html input tag

I want to perform this operation but value attribute is not working

<input name="grand_total" type="text" class="form-control" ng-value="@" />

<input name="discount" type="text" class="form-control" id="add_payment"  ng-model="discount1"/>

Second question If I want to send value from a P tag after html form submission, how can I do that and how can I retrieve that value? I want to pass this value @ to my controller and want to store it into my database. Here is the code portion

<div class="form-group">
     <label for="grand_total" class="col-sm-4 control-label">Discount</label>
     <div class="col-sm-8">
           <p class="form-control-static" ><b>@</b></p>
      </div>
</div>

via Chebli Mohamed