//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);
}