import sys
from functools import lru_cache

input = sys.stdin.buffer.readline

sys.setrecursionlimit(4100000)
n = int(input())
A = list(map(int, input().split()))

A.sort(reverse=True)


@lru_cache(None)
def calc(bit):
    # print("bit", bit)
    if bit == (1 << n) - 1:
        return 1
    res = 0
    mx = -1
    for i in range(n):
        if (bit >> i) & 1:
            mx = max(mx, A[i])
    ok = 0
    ng = 0
    for i in range(n):
        if (bit >> i) & 1:
            continue
        if A[i] >= mx:
            ok += 1
        else:
            ng += 1
    assert ok + ng > 0
    # ratio = 1 / (ok + ng)
    for i in range(n):
        if (bit >> i) & 1:
            continue
        nbit = bit | (1 << i)
        if A[i] >= mx:
            res += (ok + ng) * (calc(nbit))
    return res


cnt = 100
ok = 1
ng = 0
print(calc(0))