import sys
input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
yes = lambda :print("yes");Yes = lambda :print("Yes");YES = lambda : print("YES")
no = lambda :print("no");No = lambda :print("No");NO = lambda : print("NO")
######################################################################
mod = 998244353
nn = 10 ** 6
fact = [1] * nn
for i in range(nn - 1):
    fact[i + 1] = fact[i] * (i + 1) % mod
invfact = [1] * nn
invfact[nn - 1] = pow(fact[nn - 1], mod - 2, mod)
for i in range(nn - 1)[::-1]:
    invfact[i] = invfact[i + 1] * (i + 1) % mod
 
def binom(x, y):
    if x < 0 or y < 0 or x - y < 0:
        return 0
    return fact[x] * invfact[y] % mod * invfact[x - y] % mod

def p(x, y):
    if x < 0 or x < y:
        return 0
    return fact[x] * invfact[x - y] % mod

def binom_sum(n, k): # k <= n, 
    return (n + 1 - k) * binom(n+1, n+1-k) % mod * pow(k+1, mod-2, mod) % mod

n = ni()
a = na()

f = [1] * (n+1)
f[0] = 0
for i in range(n):
    if a[i] != -1:
        f[a[i]] = 0

for i in range(1, n+1):
    f[i] += f[i-1]
M = a.count(-1)
ans = 0
z = 0
cnt = 0
for i in range(n):
    if a[i] != -1:
        if z < a[i]:
            ans += p(f[a[i]], cnt) * fact[M-cnt] % mod
            ans %= mod
        z = max(z, a[i])
    else:
        # for x in range(z+1, n+1):
        #     if x in a:
        #         continue
        #     print(cnt, x, f[x-1])
        #     #print(x, p(f[x-1], cnt) * fact[M-cnt-1] % mod)
        #     ans += p(f[x-1], cnt) * fact[M-cnt-1] % mod
        #     ans %= mod
        ans += (binom_sum(M-1, cnt) - binom_sum(f[z]-1, cnt)) * fact[M-cnt-1] % mod * fact[cnt] % mod
        ans %= mod
        cnt += 1
    #print(ans)
print(ans)