#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
typedef long long int ll;
typedef long double ld;
#define FOR(i,l,r) for(ll i=l;i<r;i++)
#define REP(i,n) FOR(i,0,n)
#define RFOR(i,l,r) for(ll i=r-1;i>=l;i--)
#define RREP(i,n) RFOR(i,0,n)
#define ALL(x) x.begin(),x.end()
#define P pair<ll,ll>
#define F first
#define S second
#define BS(A,x) binary_search(ALL(A),x)
#define LB(A,x) (ll)(lower_bound(ALL(A),x)-A.begin())
#define UB(A,x) (ll)(upper_bound(ALL(A),x)-A.begin())
#define COU(A,x) UB(A,x)-LB(A,x)
template<typename T>using min_priority_queue=priority_queue<T,vector<T>,greater<T>>;
//using mint=modint1000000007;
using mint=modint998244353;
signed main(){
  ll N;cin>>N;
  vector<ll>A(N),B(N);
  REP(i,N){cin>>A[i];B[A[i]]=i;}
  mint ans=1;
  ll l=B[0],r=B[0],s=1,mex=1;
  vector<bool>seen(N+1,0);seen[0]=1;
  while(s<N){
    if(B[s]<l||r<B[s]){
      if(B[s]<l){FOR(i,B[s],l)seen[A[i]]=1;l=B[s];}
      if(B[s]>r){FOR(i,r+1,B[s]+1)seen[A[i]]=1;r=B[s];}
      ll k=mex;while(seen[mex])mex++;
      REP(i,mex-k-1)ans*=r-l-s-i;
    }
    //cout<<s<<" "<<ans.val()<<endl;
    s++;
  }
  cout<<ans.val()<<endl;
  return 0;
}