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