Unchecked angularJS Checkbox When Select Option CHanges

<select ng-model="select">
    <option value="1"></option>
    <option value="2"></option>
    <option value="3"></option>
</select>

when select value is 1,3 I want to show the checkbox

<input type=checkbox name="ccp" ng-model="ccp" ng-show="select.val==1 || select.val==2">

the Problem is when I select 1 then checkbox is visible, and I checked the checkbox. but when I change the select option the checkbox is invisible but its with checked. I want when I select option changes I want uncheck the checkbox.