#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;
using ll = long long;
using ld = long double;

#define all(x)  x.begin(),x.end()
#define v(x) vector<x>
#define nl '\n'
#define fxd(x) fixed << setprecision(x)
template<class t> using ordered_set = tree<t, null_type, less<t>, rb_tree_tag, tree_order_statistics_node_update>;
template<class t> using ordered_multiset = tree<t, null_type, less_equal<t>, rb_tree_tag, tree_order_statistics_node_update>;


int main()
{
    ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
    int n; cin >> n;
    v(ll) a(n);
    for (int i = 0; i < n; i++)
    {
        cin >> a[i];
    }
    ll l = 0 , sl = 0 , sr = 0, mx =0 , r = n-1;
    while (l <= r)
    {
        if(sl <= sr)
        {
            sl+= a[l];
            l++;
        }
        else
        {
            sr += a[r];
            r--;
        }
        if(sl == sr)
        {
            mx = sl;
        }
    }
    cout << mx;
}