Angularjs Selecting two checkboxes from multiple checkboxes

I need to select only two check boxes from the given multiple checkboxes and are not embedded in the list.

<input type="checkbox" class="two-checkbox" id="curr-EUR" ng-model="reqObject.EUR" ng-click="checkChanged()">EUR</input>
<input type="checkbox" class="two-checkbox" id="curr-JPY" ng-model="reqObject.JPY" ng-click="checkChanged()">JPY</input>
<input type="checkbox" class="two-checkbox" id="curr-INR" ng-model="reqObject.INR" ng-click="checkChanged()">INR</input>
<input type="checkbox" class="two-checkbox" id="curr-USD" ng-model="reqObject.USD" ng-click="checkChanged()">USD</input>

The above are my checkboxes and I need to select only two from them in angular way.