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

if(marks > 90){
    console.log("AA");
}

else if(marks >80 && marks<=90){
    console.log("AB");
}

else if(marks >70 && marks<=80){
    console.log("BB");
}



else if(marks >60 && marks<=70){
    console.log("BC");
}

else if(marks >50 && marks<=60){
    console.log("CC");
}

else if(marks >40 && marks<=50){
    console.log("CD");
}

else if(marks >30 && marks<=40){
    console.log("DD");
}
else{
    console.log("FF");
}