"""


"""

import sys
from sys import stdin

N = int(stdin.readline())

A = list(map(int,stdin.readline().split()))

one = 0
two = 0
other = 0

for i in A:
    if i == 2:
        two += 1
    elif i == 1:
        one += 1
    else:
        other += 1

ans = 0
ans += 2 * (one * (one-1)//2)
ans += 2 * (one * other)
ans += 3 * (one * two)
ans += 1 * ( N*(N-1)//2 - one * (one-1)//2 - one * two - one * other)
print (ans)