from collections import Counter

N = int(input())
A = list(map(int, input().split()))
ac = Counter()
for a in A:
    ac[min(3, a)] += 1

ans = 0
ans += ((ac[1]**2)-ac[1])//2 * 2
ans += ((ac[2]**2)-ac[2])//2
ans += ((ac[3]**2)-ac[3])//2
ans += ac[1]*ac[2] * 3
ans += ac[1]*ac[3] * 2
ans += ac[2]*ac[3]

print(ans)