n = int(input())
A = sorted(map(int, input().split()))
x = A.count(1)
y = A.count(2)
z = n - x - y
ans = y*(y-1)//2 + y*z + z*(z-1)//2
ans += 2 * (x*(x-1)//2 + x*z)
ans += 3 * x*y
print(ans)