//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");
}