You are given an array $d_1, d_2, \dots, d_n$ consisting of $n$ integer numbers.

Your task is to split this array into three parts (some of which may be empty) in such a way that each element of the array belongs to exactly one of the three parts, and each of the parts forms a consecutive contiguous subsegment (possibly, empty) of the original array. 

Let the sum of elements of the first part be $sum_1$, the sum of elements of the second part be $sum_2$ and the sum of elements of the third part be $sum_3$. Among all possible ways to split the array you have to choose a way such that $sum_1 = sum_3$ and $sum_1$ is maximum possible.

More formally, if the first part of the array contains $a$ elements, the second part of the array contains $b$ elements and the third part contains $c$ elements, then:

$$sum_1 = \sum\limits_{1 \le i \le a}d_i,$$ $$sum_2 = \sum\limits_{a + 1 \le i \le a + b}d_i,$$ $$sum_3 = \sum\limits_{a + b + 1 \le i \le a + b + c}d_i.$$

The sum of an empty array is $0$.

Your task is to find a way to split the array such that $sum_1 = sum_3$ and $sum_1$ is maximum possible.
The first line of the input contains one integer $n$ ($1 \le n \le 2 \cdot 10^5$) — the number of elements in the array $d$.

The second line of the input contains $n$ integers $d_1, d_2, \dots, d_n$ ($1 \le d_i \le 10^9$) — the elements of the array $d$.
5
1 3 1 1 4
5
5
1 3 2 1 4
4
3
4 1 2
0
1
1000000000
0
2
1 1
1
5
1 3 5 4 5
9
def solve():
    n = inp()
    l = seq()
    total = sum(l)
    sum1 = 0
    sum3 = 0
    low = 0
    high = n-1
    maxi = 0
    while(low<high):
        if(sum1==sum3):
            maxi = max(sum1,maxi)
            sum1+=l[low]
            sum3+=l[high]
            low+=1
            high-=1
        elif(sum1<sum3):
            sum1+=l[low]
            low+=1
        else:
            sum3+=l[high]
            high-=1
    if(sum1==sum3):
        maxi = max(sum1,maxi)
    print(maxi)
import sys
import math
import bisect
from sys import stdin,stdout
from math import gcd,floor,sqrt,log
from collections import defaultdict as dd
from bisect import bisect_left as bl,bisect_right as br

inp    =lambda: int(input())
strng  =lambda: input().strip()
jn     =lambda x,l: x.join(map(str,l))
strl   =lambda: list(input().strip())
mul    =lambda: map(int,input().strip().split())
mulf   =lambda: map(float,input().strip().split())
seq    =lambda: list(map(int,input().strip().split()))

ceil   =lambda x: int(x) if(x==int(x)) else int(x)+1
ceildiv=lambda x,d: x//d if(x%d==0) else x//d+1

flush  =lambda: stdout.flush()
stdstr =lambda: stdin.readline()
stdint =lambda: int(stdin.readline())
stdpr  =lambda x: stdout.write(str(x))

solve()



