Shared code

/*
  author: @ankingcodes
  created: 2021-07-14 19:51:14.168996
*/
        
#include<bits/stdc++.h>
#include<algorithm>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>

using namespace __gnu_pbds;
using namespace std;
#define ll long long
#define MOD 1000000007

typedef tree<int, null_type, less<int>, rb_tree_tag,
                tree_order_statistics_node_update> PBDS;

typedef tree<pair<int, int>, null_type, less<pair<int, int>>, rb_tree_tag,
                tree_order_statistics_node_update> pairPBDS;

int main(){
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  ll n, x = 1; cin>>n;
  vector<ll> a(n), pf(n);
  for (auto &i: a) {
    cin>>i;
    pf[x] = pf[x-1] + i;
    x += 1;
  }
  ll mxs = pf[1];
  ll mxp = pf[0];
  for (auto x: pf) {
    mxs = max(mxs, x-mxp);
    mxp = min(mxp, x);
  }
  cout << mxs << endl;
  return 0;
}