#!/usr/bin/env python3
from collections import defaultdict

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

countA = defaultdict(int)

for a in A:
    countA[a] += 1

ret = 1
for i in range(N):
    ret *= i + 1

for key, val in countA.items():
    for i in range(val):
        ret //= i + 1

print(ret)