from bisect import bisect_left, bisect_right
from collections import Counter
N = int(input())
a = sorted(map(int, input().split()))

i, j = bisect_left(a, 0), bisect_right(a, 0)
minus, zero, plus = [-n for n in a[:i]], a[i:j], a[j:]
ans = [0, 0, len(zero)//2]

_a = (zero+plus)[::-1]
i = j = 0
for j, m in enumerate(minus):
    while i < len(_a) and _a[i] >= m:
        i += 1
    if i == len(_a):
        break
    ans[0] += 1
    i += 1
ans[0] += (max(0, len(minus)-j) // 2)

_a = zero + minus[::-1]
i = j = 0
for j, p in enumerate(plus[::-1]):
    while i < len(_a) and _a[i] >= p:
        i += 1
    if i == len(_a):
        break
    ans[1] += 1
    i += 1
ans[1] += (max(0, len(plus)-j) // 2)

minus_counter, plus_counter = Counter(minus), Counter(plus)
ans[2] += sum(min(v, plus_counter[k]) for k, v in minus_counter.items())