ng-model overwritten within ng-repeat

I have a table with an input field, I'm setting values to ng-model in each iteration of ng-repeat. I'm getting correct values in each iteration, but all of the ng-model values are overwritten by the last value of iteration. How can I solve this ?

view

<tr ng-repeat="student in students_list">
        <td>{{student.Rollnumber}}</td>
        <td>{{student.Name}}</td>
        <td ng-repeat="item in Allsubjects" >      
            <input   type="text" class="form-control" ng-model="da" 
                  ng-init="alert(student.Id)">
        </td>
</tr>

controller

$scope.alert = function(id)
{
    $scope.da =id;
};

This is What I'm getting (screenshot):

331 is the result of last iteration. It is overwriting previous values.

Yes, it is expected behaviour that last value of the iteration will be assigned to "da"

You can resolve this by

<tr ng-repeat="student in students_list">
        <td>{{student.Rollnumber}}</td>
        <td>{{student.Name}}</td>
        <td ng-repeat="item in Allsubjects" >      
            <input   type="text" class="form-control" ng-model="student['da']" 
                  ng-init="alert(student)">
        </td>
</tr> 

and the alert function

$scope.alert = function(student)
{
    student["da"] = student.id;
};

Here, we are just creating a new property named "da"(took name you used) for every object of student in student_list array, so it will have value respective to it's object.