n = int(input())
A = list(map(int, input().split()))

F = [1 for _ in range(n + 1)]
for i in range(2, n + 1):
    F[i] = i * F[i - 1]

A.sort()
ans = F[n]
cnt = 1
for i in range(1, n):
    if A[i] == A[i - 1]:
        cnt += 1
        if i == n - 1:
            ans //= F[cnt]
    else:
        ans //= F[cnt]
        cnt = 1
print(ans)