N = int(input())
A = list(map(int, input().split()))
X = [0] * 4
ans = 0
for i in reversed(range(N - 1)):
    X[min(A[i + 1], 3)] += 1
    c = N - i - 1
    if A[i] == 1:
        ans += 2 * (X[1] + X[3])
        ans += 3 * X[2]
    elif A[i] == 2:
        ans += X[2] + X[3]
        ans += 3 * X[1]
    else:  # A[i] >= 3
        ans += X[2] + X[3]
        ans += 2 * X[1]
print(ans)