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

dict = {}

for i,v in enumerate(A):
    if v not in dict:
        dict[v] = 1
    else:
        dict[v]+=1

bunbo = 1
bunshi = 1
nokori = N

for i,v in enumerate(A):

    if dict[v] == 1:
        bunbo*=nokori
        bunshi*=1
        nokori-=1
    else:
        bunbo*=nokori
        bunshi*=dict[v]
        dict[v]-=1
        nokori-=1

ans = bunbo//bunshi

print(ans)