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

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

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