//#include <ext/pb_ds/assoc_container.hpp> 
//#include <ext/pb_ds/tree_policy.hpp> 
//using namespace __gnu_pbds; 
//#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update> 
#include <bits/stdc++.h>
using namespace std;
//#define int long long
#define dd double
#define ld long double
#define ull unsigned long long
#define yes cout << "YES\n"
#define no cout << "NO\n"
#define el "\n"
#define Arwa ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define fix(x) cout << fixed << setprecision(x)
#define all(v) v.begin(),v.end()
void file() 
{
    #ifndef ONLINE_JUDGE
        freopen("input.txt", "r", stdin);
        freopen("output.txt", "w", stdout);
    #endif
}
int gcd(int a, int b) { return b == 0 ? a : gcd(b, a % b); }
int lcm(int a, int b) { return a / gcd(a, b) * b; }
bool prime(int n) {
    if (n == 2) return true;
    if (n % 2 == 0 || n == 1) return false;
    for (int i = 3; i * i <= n; i += 2)
        if (n % i == 0) return false;
    return true;
}
//Here We Go Again
int32_t main() 
{
    Arwa
    int t=1;
    //cin>>t;
    while(t--) 
    {
      int n;
      cin>>n;
      int arr[n];
      map<int,bool>m1,m2;
      for(int i=0;i<n;i++)
      cin>>arr[i];
      bool f=1;
      int s=0,e=n-1,sum1=0,sum2=0,mx=-1e9;
      while(s<=e)
      {
        if(f)
        {
        sum1+=arr[s];
        s++;
        f=0;
        }
        else
        {
        sum2+=arr[e];
        e--;
        f=1;
        }    
        m1[sum1]=1;
        m2[sum2]=1;
        if(m2[sum1])
        mx=max(mx,sum1);
        if(m1[sum2])
        mx=max(mx,sum2);   
      }
      cout<<max(mx,0)<<el;
    }
    return 0;
}