N=int(input())
A=list(map(int,input().split()))
mod=998244353
v=[0]*(N+1)
for i in range(N):
  x=A[i]
  v[x]+=1
B=[0]*(N+1)
for x in range(1,N+1):
  if v[x]<v[x-1]:
    print(0)
    exit()
  B[x]=v[x]-sum(B[:x])
u=[1]*(N+1)
u2=[1]*(N+1)
for i in range(1,N+1):
  u[i]=u[i-1]*i
  u[i]%=mod
  u2[i]=pow(u[i],-1,mod)
def ncm(x,y):
  ans=u[x]*u2[y]
  ans%=mod
  ans*=u2[x-y]
  ans%=mod
  return ans
p=[0]*(N+1)
C=B[:]
w=1
c=0
t=0
for k in range(1,N+1):
  if C[k]==0:
    continue
  if c==0:
    c=C[k]
    t=k
  else:
    b=C[k]
    w*=ncm(b+c-1,c-1)
    w%=mod
    c+=C[k]
result=w
for k in range(1,N+1):
  if v[k]==0:
    continue
  if k==t:
    result*=u[v[k]-1]
    result%=mod
  else:
    result*=u[v[k]]
    result%=mod
result*=N
result%=mod
print(result)