How to get selected value from select box in angularjs

Hello everyone

I'm trying to get option value from select box on button click but it shows undefined in console. The option value comes from the server

Here is my HTML code

<div class="form-group">
        <label class="control-form" for="cityid">Selct City</label>
        <select type="text" class="form-control" placeholder="City" id="acity" >
            <option value="">--Select City--</option>
            <option ng-repeat="city in cityinfo" ng-value="{{city.id}}"  ng-selected="{{city.id ==cityid}}">{{city.cityname}}</option>
</select>

<button class="btn btn-info prevnext pull-right" ng-click="nextpage()">Next <i class="fa fa-arrow-right"></i></button>

Controller.js file code

  $scope.nextpage = function(pageno) {
   console.log($scope.cityinfo);
   }

Thanks in advance