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

x=A.count(1)
y=A.count(2)
z=N-(x+y)

X=2*x*(x-1)//2+3*x*y+2*x*z
X+=y*(y-1)//2+y*z
X+=z*(z-1)//2

print(X)