//Do not declare variable marks.
//Write your code below this line.
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")
}