angular-select.html

<select id='country-selection' 
  ng-options="option.name for option in vm.countries track by option.code" 
  ng-model="vm.selectedCountries"
  material-select 
  multiple 
  name="country_selection" required>
  
  <option disabled value="">Select visitor country (max 3)</option>
</select>

<div ng-if="vm.selectedCountries.length > 3">
  <span class="error-text">/Max 3 countries/</span>
</div>

<div ng-messages="JAMON.$error" ng-if="vm.showErrors" role="alert">
  <div ng-messages-include="error-messages"></div>
</div>