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

if (marks > 90) {
    console.log("AA");
} else if (90 >= marks >80) {
    console.log("AB");
} else if (80 >= marks >70) {
    console.log("BB");
} else if (70 >= marks >60) {
    console.log("BC");
} else if (60 >= marks >50) {
    console.log("CC");
} else if (50 >= marks >40) {
    console.log("CD");
} else if (40 >= marks >30) {
    console.log("DD");
} else if (30 >= marks) {
    console.log("FF");
}