#include <bits/stdc++.h>
using namespace std;

template <typename A, typename B>
string to_string(pair<A, B> p);
 
template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p);
 
template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p);
 
string to_string(const string& s) {
  return '"' + s + '"';
}
 
string to_string(const char* s) {
  return to_string((string) s);
}
 
string to_string(bool b) {
  return (b ? "true" : "false");
}
 
string to_string(vector<bool> v) {
  bool first = true;
  string res = "{";
  for (int i = 0; i < static_cast<int>(v.size()); i++) {
    if (!first) {
      res += ", ";
    }
    first = false;
    res += to_string(v[i]);
  }
  res += "}";
  return res;
}
 
template <size_t N>
string to_string(bitset<N> v) {
  string res = "";
  for (size_t i = 0; i < N; i++) {
    res += static_cast<char>('0' + v[i]);
  }
  return res;
}
 
template <typename A>
string to_string(A v) {
  bool first = true;
  string res = "{";
  for (const auto &x : v) {
    if (!first) {
      res += ", ";
    }
    first = false;
    res += to_string(x);
  }
  res += "}";
  return res;
}
 
template <typename A, typename B>
string to_string(pair<A, B> p) {
  return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}
 
template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p) {
  return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ")";
}
 
template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p) {
  return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ", " + to_string(get<3>(p)) + ")";
}
 
void debug_out() { cerr << endl; }
 
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
  cerr << " " << to_string(H);
  debug_out(T...);
}
#ifdef LOCAL
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif

#define fi first
#define se second
#define pb push_back
#define mod(n,k) ( ( ((n) % (k)) + (k) ) % (k))
#define forn(i,a,b) for(int i = a; i < b; i++)
#define forr(i,a,b) for(int i = a; i >= b; i--)
#define all(x) (x).begin(), (x).end()

typedef long long ll;
typedef long double ld;
typedef pair<int,int> ii;
typedef vector<int> vi;
typedef vector<ii> vii;

const ll mod = 1e9+7;
ll mul(ll a,ll b){return ((a%mod)*(b%mod))%mod;}
ll sum(ll a,ll b){return ((a%mod)+(b%mod))%mod;}
ll sub(ll a,ll b){return ((a%mod)-(b%mod))%mod;}
ll power(ll a,ll b){
	ll res = 1;
	while(b){
		if(b&1)res = mul(res,a);
		b >>= 1;
		a = mul(a,a);
	}
	return res;
}

int main(){
	ios_base::sync_with_stdio(0); cin.tie(0);
	int N; cin >> N;
	vector<ll> A(N),sum(N),maxi(N);
	forn(i,0,N)cin >> A[i];
	forn(i,0,N){
		sum[i] = A[i];
		if(i)sum[i] += sum[i-1];
		maxi[i] = sum[i];
		if(i)maxi[i] = max(maxi[i],maxi[i-1]);
	}
	debug(sum);
	debug(maxi);
	ll res = 0;
	ll pos = 0;
	forn(i,0,N){
		res = max(res,pos+maxi[i]);
		debug(i,pos,sum[i],maxi[i]);
		pos += sum[i];
	}
	cout << res << '\n';
	return 0;
}
/*
__builtin_mul_overflow(x,y,&x)
-fsplit-stack
*/

#include <bits/stdc++.h>
using namespace std;
#define ll long long int
#define pb push_back
#define ff first
#define ss second
int main(void){
    // Your code here!
 ll i,ans,n;
 cin >> n;
 ll a[n],b[n];
 for(i=0;i<n;i++)
 {
  cin >> a[i];
  b[i]=a[i];
 }
 for(i=1;i<n;i++)
 {
  a[i]+=a[i-1];
  b[i]+=b[i-1];
 }
 for(i=1;i<n;i++)
 {
  a[i]=max(a[i],a[i-1]);
  b[i]+=b[i-1];
 }
 ans=0;
 ans=max(ans,a[0]);
 ans=max(ans,b[n-1]);
 for(i=0;i<(n-1);i++)
 ans=max(ans,b[i]+a[i+1]);
 cout << ans;
 return 0;
}