//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");
}