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

if(marks > 90) console.log("AA");
else if(marks>80) console.log("BB");
else if(marks>70) console.log("CC");
else if(marks>60) console.log("CC");
else if(marks>50) console.log("CD");
else if(marks>40) console.log("DD");
else if(marks>30) console.log("FF");
else console.log(FF);