N = int(input())
A = list(map(int,input().split()))
C = {}
for i in range(N):
    C[A[i]] = C.get(A[i],0)+1
A = [1]*(N+1)
for i in range(2,N+1):
    A[i] = i*A[i-1]
ans = A[N]
for i in C:
    ans //= A[C[i]]
print(ans)