def ilog2(n):
  return 0 if n <= 0 else n.bit_length() - 1

def pack(pack, shamt):
  size = len(pack)
  while size > 1:
    npack = []
    for i in range(0, size - 1, 2):
      npack += [pack[i] | (pack[i+1] << shamt)]
    if size & 1:
      npack += [pack[-1]]
    pack, size, shamt = npack, (size + 1) >> 1, shamt << 1
  return pack[0]

def unpack(M, size, shamt):
  s, sizes = size, []
  while s > 1:
    sizes += [s]
    s = (s + 1) >> 1
  ret = [M]
  for size in sizes[::-1]:
    mask, nret = (1 << shamt) - 1, []
    for c in ret:
      nret += [c & mask, c >> shamt]
    ret, shamt = nret[:size], shamt >> 1
  return ret

def poly_mul_mod(f, g, mod):
  size = min(len(f), len(g))
  shift = ((mod - 1) ** 2 * size).bit_length()
  rsize = len(f) + len(g) - 1
  h = unpack(pack(f, shift) * pack(g, shift), rsize, shift * (1 << ilog2(rsize - 1)))
  return [int(x % mod) for x in h]

def poly_coefficients_mod(roots, mod):
  def rec(beg, end):
    if end - beg == 1:
      return [1, -roots[beg] % mod]
    else:
      mid = (beg + end) // 2
      return poly_mul_mod(rec(beg, mid), rec(mid, end), mod)

  if not roots:
    return [1]

  ret = [0] * (len(roots) + 1)
  return rec(0, len(roots))

def prob243():
  from sys import stdin

  N = int(stdin.readline())
  MOD = 10 ** 9 + 7

  cnts = [0] * 5000
  for line in stdin:
    a = int(line)
    cnts[a] += 1

  roots = []
  for i in range(N):
    if cnts[i]:
      roots += [-cnts[i]]

  poly = poly_coefficients_mod(roots, MOD)

  facts = [1]
  for i in range(1, N + 1):
    facts += [facts[-1] * i % MOD]

  ans = 0
  for i in range(len(poly)):
    ans += (-1) ** i * poly[i] * facts[-1 - i] % MOD

  print(ans % MOD)

prob243()