I'm not sure how to get an element of the type that repeats within the same page. I tried using the following XPath's that were validated in FirePath, but I was not successful when I ran my tests through selenium.
//div[@id='selectGenericMult']/child::div/child::input']
(.//*[@id='selectGenericMult']/child::div/child::input)[last()]
The tag data you are trying to get is these:
<input class="ui-select-search input-xs ng-pristine ng-valid ng-touched" autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false" placeholder="Selecione" ng-disabled="$select.disabled" ng-hide="$select.disabled" ng-click="$select.activate()" ng-model="$select.search" role="combobox" aria-label="Select box" ondrop="return false;" style="width: 1331px;" type="text"/>