#include<bits/stdc++.h>
using namespace std;
const int N=5e5+5,Mod=998244353,iM=(Mod+1)>>1;
typedef long long ll;
ll a[N],pre[N],suf[N];
inline int po(int x, int y)
{
    int r=1;
    for(;y;y>>=1,x=1ll*x*x%Mod) if(y&1) r=1ll*r*x%Mod;
    return r;
}
set<pair<int,ll>> s;
priority_queue<pair<ll,int>> q;
int main()
{
    int n; scanf("%d",&n);
    for(int i=1;i<=n;++i) scanf("%lld",&a[i]);
    int ans=(a[1]+a[n])%Mod;
    s.insert(make_pair(1,a[1]));
    s.insert(make_pair(n,a[n]));
    for(int i=2;i<n;++i) q.push(make_pair(a[i],i));
    while(!q.empty())
    {
        ll w=q.top().first;
        int i=q.top().second;
        q.pop();
        auto itr=s.lower_bound(make_pair(i,0)),itl=itr; --itl;
        ll w2=itr->second+itl->second;
        if(w2 > 2ll*w) ans=(ans+w2%Mod*iM)%Mod;
        else ans=(ans+w)%Mod,s.insert(make_pair(i,w));
    }
    printf("%d\n",1ll*ans*po(n,Mod-2)%Mod);
}