#include<iostream>
#include<cstdio>
#include<cmath>
#include<algorithm>
#define ll long long 

const int N = 20001;

using namespace std;

inline ll read(){
    ll s=0,w=1; char ch=getchar();
    while(ch<'0'||ch>'9'){if(ch=='-') w=-1; ch=getchar();}
    while(ch>='0'&&ch<='9'){s=(s<<1)+(s<<3)+(ch^48); ch=getchar();}
    return s*w;
}

ll n, m, s[N], ans;

inline void init(){
    n=read();
    for(int i=1;i<=n;i++) s[i]=read();
}

inline ll work(){
    if(n==3) {ans+=s[1]+s[2]+s[3]; return ans;}
    ans=s[1]+s[2];
    for(int i=3;i<=n;i++){
        if(s[i]<ans-s[i-1]) continue;
        if(s[i]>ans-s[i-1]) ans=s[i]+s[i-1];
//      if(i==n){
//          if(ans-s[n-1]-s[1]>s[n]) continue;
//          if(ans-s[n-1]-s[1]<s[n]) ans=s[n]+s[n-1]+s[1];
//      }
    }
    for(int i=1;i<=n;i++) m+=s[i];
    double mm=m,nn=n,sum;
    sum=ceil(mm/(int)(nn/2));
    if((int) sum>ans) ans=(int)sum;
    return ans;
}

int main(){
    init();
    printf("%lld",work());
    return 0;
}