//Do not declare variable marks.
//Write your code below this line.
var p;
if(marks>90)
    p="AA";
else if(marks >80)
    p="AB";
else if(marks>70)
    p="BB";
else if(marks >60)
    p="BC";
else if(marks >50)
    p="CC";
else if(marks >40)
    p="CD";
    else if(marks >30)
           p="DD";
else
    p="FF";
console.log(p);