//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 if (marks <=30){
    
    console.log("FF");
}