import sys,random,bisect
from collections import deque,defaultdict
from heapq import heapify,heappop,heappush
from itertools import permutations
from math import gcd,log

input = lambda :sys.stdin.readline().rstrip()
mi = lambda :map(int,input().split())
li = lambda :list(mi())

def cmb(n, r, mod):
    if ( r<0 or r>n ):
        return 0
    return (g1[n] * g2[r] % mod) * g2[n-r] % mod


mod = 998244353
N = 3*10**5
g1 = [1]*(N+1)
g2 = [1]*(N+1)
inverse = [1]*(N+1)

for i in range( 2, N + 1 ):
    g1[i]=( ( g1[i-1] * i ) % mod )
    inverse[i]=( ( -inverse[mod % i] * (mod//i) ) % mod )
    g2[i]=( (g2[i-1] * inverse[i]) % mod )
inverse[0]=0

def solve(N,A):
    A_use = [0] * (N+1)
    for a in A:
        if a!=-1:
            A_use[a] = 1

    rest_cnt_lower = [0] * (N+1)
    for a in range(1,N+1):
        if not A_use[a]:
            rest_cnt_lower[a] += 1
    for a in range(1,N+1):
        rest_cnt_lower[a] += rest_cnt_lower[a-1]
    
    res = 0
    tmp_a_max = 0
    vac_cnt = 0
    n = rest_cnt_lower[-1]
    for i in range(N):
        if A[i] == -1:
            vac_cnt += 1
            res += g1[n] * inverse[vac_cnt] % mod - cmb(rest_cnt_lower[tmp_a_max],vac_cnt,mod) * (g1[vac_cnt-1] * g1[n-vac_cnt] % mod) % mod
            res %= mod
        else:
            tmp_a_max = max(tmp_a_max,A[i])
            if tmp_a_max == A[i]:
                res += cmb(rest_cnt_lower[tmp_a_max],vac_cnt,mod) * (g1[vac_cnt] * g1[n-vac_cnt] % mod) % mod
                res %= mod
    return res


N = int(input())
A = li()
print(solve(N,A))