//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");  
}