//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")
    }