//Do not declare variable marks.
//Write your code below this line.
if(marks<=30)
    console.log("FF");
else if(marks>30&&marks<=40)
    consloe.log("DD");
else if(marks>40&&marks<=50)
    consloe.log("CD");
else if(marks>50&&marks<=60)
    consloe.log("CC");
else if(marks>60&&marks<=70)
    consloe.log("BC");
else if(marks>70&&marks<=80)
    consloe.log("BB");
else if(marks>80&&marks<=90)
    consloe.log("AB");
else
    console.log("AA");