#include <bits/stdc++.h> using namespace std; using ll = long long; const ll MOD = 998244353; using P = pair<int,int>; #define rep(i, n) for(int i = 0; i < n; i++) #define all(x) (x).begin(),(x).end() template<class T>bool chmin(T&a, const T&b){if(a>b){a=b;return 1;}return 0;} template<class T>bool chmax(T&a, const T&b){if(a<b){a=b;return 1;}return 0;} int main(){ int n; cin >> n; vector<int> ainv(n); rep(i,n){ int a; cin >> a; ainv[a] = i; } int be = min(ainv[0],ainv[1]), en = max(ainv[0],ainv[1]); ll ans = 1; for(int i=2;i<n;i++){ if(chmin(be,ainv[i])) continue; else if(chmax(en,ainv[i])) continue; else ans = (ans * (en - be - i + 1)) % MOD; } cout << ans << endl; return 0; }