import sys

def resolve():
    _ = input()
    cnt1,cnt2,cntother = 0,0,0
    for ai in map(int,sys.stdin.readline().split()):
        if ai == 1: cnt1 += 1
        elif ai == 2: cnt2 += 1
        else: cntother += 1

    result = 0
    if cnt1 > 1:
        result += cnt1*(cnt1-1)

    result += cnt1 * cnt2 * 3 + cnt1 * cntother * 2\
        + (cnt2 + cntother) * (cnt2 + cntother - 1) // 2

    print(result)

resolve()