n = int(input())
a = list(map(int, input().split()))
mod = 998244353
place = {}
for i in range(n):
    place[a[i]] = i

ans = 1
l = place[0]
r = place[0]
for i in range(1, n):
    l_nxt = min(l, place[i])
    r_nxt = max(r, place[i])
    if l == l_nxt and r == r_nxt:
        ans *= r - l + 1 - i
        ans %= mod 
    l = l_nxt
    r = r_nxt

print(ans)