## https://yukicoder.me/problems/no/2944


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

    a_counts = [0] * 4
    for a in A:
        x = min(a, 3)
        a_counts[x] += 1

    answer = 0
    # 回答が一
    n = a_counts[2] + a_counts[3]
    answer += (n * (n - 1)) // 2

    # 回答が2
    answer += 2 * a_counts[1] * a_counts[3]
    n = a_counts[1]
    answer += 2 * ((n * (n - 1)) //2)

    # 回答3
    answer += 3 * a_counts[1] * a_counts[2]
  

    print(answer)


if __name__ == "__main__":
    main()