import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long[] dl = new long[100001];
		long[] dr = new long[100001];
		long[] a = new long[100001];
		int n = sc.nextInt();
		for (int i = 1; i <= n; i++) {
			a[i] = sc.nextLong();
		}
		for (int i = 1; i <= n; i++) {
			dl[i] = Math.max(dl[i - 1] + a[i], a[i]);
		}
		for (int i = n; i >= 1; i--) {
			dr[i] = Math.max(dr[i + 1] + a[i], a[i]);
		}
		long max = -1000;
		for (int i = 1; i <= n - 1; i++) {
			if (dl[i - 1] + dr[i + 1] > max) {
				max = dl[i - 1] + dr[i + 1];
			}
		}
		for (int i = 1; i <= n; i++) {
			if (dl[i] > max) {
				max = dl[i];
			}
		}
		System.out.println(max);
		sc.close();
	}
}