//Do not declare variable marks.
//Write your code below this line.
if(marks > 90)
    {AA}
else if(marks > 80 && <= 90)
    {AB}
else if(marks > 70 && <= 80)
    {BB}
else if(marks > 60 && <= 70)
    {BC}
else if(marks > 50 && <= 60)
    {CC}
else if(marks > 40 && <= 50)
    {CD}
else if(marks > 30 && <= 40)
    {DD}
else if(marks <= 30)
    {FF}