//Do not declare variable marks.
//Write your code below this line.
var marks="100";
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 && marks ==30){console.log("FF");}