<Class>
    <student rollno='1'>ABC</student>
    <student rollno='1'>PQR</student>
    <student rollno='8'>XYZ</student>
    <student rollno='1'>ABC</student>
</Class>

<Class>
    <student rollno='1'>ABC</student>
    <student rollno='1'>PQR</student>
    <student rollno='8'>XYZ</student>
</Class>