import bisect

n = int(input())
a = list(map(int, input().split()))
a_set = set(a)

assert 1 <= n <= 2 * 10**5
assert len(a) == n
assert all(x == -1 or 1 <= x <= n for x in a)
assert len(a_set - {-1}) == sum(x != -1 for x in a)

mod = 998244353
max_frac = 10 ** 6
frac = [1]
for i in range(1, max_frac + 1):
    frac.append(frac[-1] * i % mod)

def comb(a, b):
    if a < b or a < 0 or b < 0:
        return 0
    return frac[a] * pow(frac[b] * frac[a - b], -1, mod) % mod

a_set = set(a)
not_a = sorted([i for i in range(1, n + 1) if i not in a_set])
not_a_len = len(not_a)

prefix_max = 0
prefix_neg = 0
ans = 0
for i, x in enumerate(a):
    if x == -1:
        not_a_pos = max(bisect.bisect_left(not_a, prefix_max), prefix_neg)
        ans += (comb(not_a_len, prefix_neg + 1) - comb(not_a_pos, prefix_neg + 1)) * frac[not_a_len - prefix_neg - 1] * frac[prefix_neg]
        # print(i, x, (comb(not_a_len + 2, not_a_pos - prefix_neg + 2) - comb(not_a_pos + 1, not_a_pos - prefix_neg + 2)) * frac[not_a_len - prefix_neg] * frac[prefix_neg])
        # print(f"{i=} {x=} {not_a_pos=} {prefix_neg=} {ans=}")
        # print(comb(not_a_len, prefix_neg + 1) - comb(not_a_pos, prefix_neg), frac[not_a_len - prefix_neg - 1], frac[prefix_neg])
    else:
        if prefix_max < x:
            not_a_pos = bisect.bisect_left(not_a, x)
            ans += comb(not_a_pos, prefix_neg) * frac[not_a_len - prefix_neg] * frac[prefix_neg]
        # print(i, x, comb(not_a_pos, prefix_neg) * frac[not_a_len - prefix_neg] * frac[prefix_neg])
    prefix_max = max(prefix_max, x)
    prefix_neg += x == -1

print(ans % mod)