N = int(input())
A = list(map(int,input().split()))
n1 = 0
n2 = 0
for i in range(N):
    if A[i]==1:
        n1 += 1
    elif A[i]==2:
        n2 += 1
ans = 0
ans += (N-n1)*(N-n1-1)//2
ans += n1*(n1-1)
ans += n1*n2*3
ans += n1*(N-n1-n2)*2
print(ans)