function getLetter(s) {
  let letter;
  // Write your code here
  switch (true) {
    case "aeiou".includes(s[0]):
      letter = "A";
      break;
    case "bcdefg".includes(s[0]):
      letter = "B";
      break;
    case "hijklm".includes(s[0]):
      letter = "C";
      break;
    case "nopqrstuvwxyz".includes(s[0]):
      letter = "D";
      break;
  }
  return letter;
}