//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 if (marks < 30) {
  console.log(FF);
}
}