N = int(input())

from collections import defaultdict
d = defaultdict(int)
A = list(map(int,input().split()))
for a in A:
    d[a] += 1
ans = 1
for i in range(1,N+1):
    ans *= i
for v in d.values():
    for i in  range(1,v+1):
        ans //= i
print(ans)