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

cnt_1 = A.count(1)
cnt_2 = A.count(2)
cnt_other = len(A)-cnt_1-cnt_2

ans = 0

ans += cnt_1*(cnt_1-1)//2 * 2
ans += cnt_1 * cnt_2 * 3
ans += cnt_1 * cnt_other * 2
ans += (cnt_2+cnt_other)*(cnt_2+cnt_other-1)//2

print(ans)