∀ {p : ℕ} {K : Type u} [inst : Field K] {ζ : K} [hp : Fact (Nat.Prime p)] [inst_1 : CharZero K]
  [hcycl : IsCyclotomicExtension {p} ℚ K] (hζ : IsPrimitiveRoot ζ p),
  Finite (NumberField.RingOfIntegers K ⧸ Ideal.span {hζ.toInteger - 1})