#include <bits/stdc++.h>
using namespace std;
 
int main() {
    int n;
    cin >> n;
    vector<int> b(n + 1);
 
    for (int i = 1; i <= n; i++) {
        cin >> b[i];
    }
 
    vector<int> p(n + 1, 0);
    vector<int> s(n + 1, 0);
    vector<int> u(n + 1, 0);
    vector<int> max_s(n + 1, 0);
 
    p[1] = b[1];
 
    for (int i = 2; i <= n; i++) {
        p[i] = max(b[i], b[i] + p[i - 1]);
        //cout << p[i] << endl;
    }
 
    s[n] = b[n];
    u[n] = s[n];
 
    for (int j = n - 1; j >= 1; j--) {
        if (b[j] < b[j + 1]) {
            s[j] = b[j] + s[j + 1];
        } else {
            s[j] = b[j];
        }
 
        u[j] = max(b[j], s[j]);
        max_s[j] = max(u[j], max_s[j + 1]);
    }
 
    int answer = 0;
 
    for (int i = 1; i <= n - 1; i++) {
        int l = p[i] + max_s[i + 1];
        answer = max(answer, l);
    }
 
    cout << answer << endl;
 
    return 0;
}
 

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