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

if (marks>90) {
    console.log("AA");
        //block of code if condition is true
} else if (marks>80 || marks<=90) {
      console.log("AB");//block of code if condition is false and condition_2 is true.
} else if (marks>70 || marks<=80) {
       console.log("BB");  //block of code if condition is false and condition_2 is false and condition_3 is true.
}
else if (marks>60 || marks<=70) {
      console.log("BC");//block of code if condition is false and condition_2 is true.
} else if (marks>50 || marks<=60) {
       console.log("CC");  //block of code if condition is false and condition_2 is false and condition_3 is true.
}
else if (marks>40 || marks<=50) {
      console.log("CD");//block of code if condition is false and condition_2 is true.
} else if (marks>30 || marks<=40) {
       console.log("DD");  //block of code if condition is false and condition_2 is false and condition_3 is true.
}
else {
     console.log("FF"); 
        //block of code if none of the condition(s) is true.
}