#include<bits/stdc++.h>
using namespace std;
#define int long long
void sol(){
    int n;
    cin >> n;
    int a[n];
    for(int &i:a) cin >> i;
    int l[n], r[n];
    l[0] = a[0];
    r[n - 1] = a[n - 1];
    for(int i = 1; i < n; i++) l[i] = max(l[i - 1] + a[i], a[i]);
    for(int i = n - 2; i >= 0; i--) r[i] = max(r[i + 1] + a[i], a[i]);
    int ans = -1e9;
    for(int i = 0; i < n; i++) ans = max(ans, l[i]);
    for(int i = 0; i < n; i++) ans = max(ans, r[i]);
    for(int i = 1; i < n - 1; i++) ans = max(ans, r[i + 1] + l[i - 1]);
    cout << ans << "\n";
}
signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    int t = 1;
   // cin >> t;
    while(t--){
        sol();
    }
    return 0;
}