n=int(input())
a=list(map(int,input().split()))
b=[0]*n;mod=998244353
for i in range(n):
    b[a[i]]=i
q,w=min(b[0],b[1]),max(b[0],b[1])
c=w-q-1;ans=1
for i in range(2,n):
    if b[i]>w or b[i]<q:
        q=min(q,b[i]);w=max(w,b[i])
        c=w-q-i
    else:
        ans*=c;c-=1;ans%=mod
print(ans)