from math import factorial
from collections import Counter
N = int(input())
A = list(map(int,input().split()))
D = list(Counter(A).items())
D.sort(reverse= True)
K = factorial(20)
ans = K
for x,c in D:
    while c > 0:
        ans *= N // c
        c -= 1
        N -= 1
print(ans//K)