from collections import defaultdict

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

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

D=defaultdict(int)
for a in A:
    D[a]+=1

X=F[N]
for a in D:
    X//=F[D[a]]

print(X)