import sys
import math
from math import sin, cos, tan
from functools import reduce
from collections import deque
import heapq

sys.setrecursionlimit(1000000)
intm1 = lambda x: int(x) - 1

N = int(input())
A = list(map(int, input().split()))
cnt1 = cnt2 = 0
for a in A:
	if a == 1:
		cnt1 += 1
	elif a == 2:
		cnt2 += 1
print(
	cnt2 * (cnt2 - 1) // 2 * 1
	+ cnt2 * (N - cnt1 - cnt2) * 1
	+ (N - cnt1 - cnt2) * (N - cnt1 - cnt2 - 1) // 2 * 1
	+ cnt1 * (cnt1 - 1) // 2 * 2
	+ cnt1 * (N - cnt1 - cnt2) * 2
	+ cnt1 * cnt2 * 3)