#include<bits/stdc++.h>
#define int long long
using namespace std;
const int N=200010;
pair<int,int> p[N];
int n;
bool mark[N];
bool cmp(pair<int,int> a,pair<int,int> b){return a.first>b.first;}
int minn=INT_MAX;
int jsq;
int ans;
signed main()
{
    freopen("matHS.in","r",stdin);
    freopen("matHS.out","w",stdout);
    scanf("%lld",&n);
    for(int i=1;i<=n;i++)
        scanf("%lld",&p[i].first),p[i].second=i;
    sort(p+1,p+1+n,cmp);
    for(int i=1;i<=n;i++)
    {
        if(mark[p[i].second]) continue;
        jsq++;
        minn=min(minn,p[i].first);
        mark[p[i].second-1]=1;
        mark[p[i].second+1]=1;
        ans=max(ans,p[1].first+minn+jsq);
    }
    printf("%lld",ans);
    return 0;
}