def main():
    N = int(input())
    A = list(map(int, input().split()))
    num_1_in_A = A.count(1)
    num_2_in_A = A.count(2)
    num_other_in_A = N - num_1_in_A - num_2_in_A

    sum_mex = 0

    if num_1_in_A > 1:
        sum_mex += num_1_in_A * (num_1_in_A - 1)
    sum_mex += 3 * num_1_in_A * num_2_in_A
    sum_mex += 2 * num_1_in_A * num_other_in_A

    if num_2_in_A > 1:
        sum_mex += num_2_in_A * (num_2_in_A - 1) // 2
    sum_mex += num_2_in_A * num_other_in_A

    if num_other_in_A > 1:
        sum_mex += num_other_in_A * (num_other_in_A - 1) // 2

    print(sum_mex)


if __name__ == "__main__":
    main()