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

if(marks>90)
{
    console.log("AA");
}
else if(marks>80&&<=90)
{
    console.log("AB");
}
else if(marks>70&&<=80)
{
    console.log("BB");
}
else if(marks>60&&<=70)
{
    console.log("BC");
}
else if(marks>50&&<=60)
{
    console.log("CC");
}
else if(marks>40&&<=50)
{
    console.log("CD");
}
else if(marks>30&&<=40)
{
    console.log("DD");
}
else (marks<=30)
{
    console.log("FF");
}