import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int N = scanner.nextInt();
		int[] V = new int[N + 1];

		for (int i = 1; i <= N; i++) {
			V[i] = scanner.nextInt();
		}

		int[] dp = new int[N + 1];
		dp[1] = V[1];
		for (int i = 2; i <= N; i++) {
			int max = dp[i - 1];
			for (int j = 0; j < i - 1; j++) {
				max = Math.max(max, dp[j] + V[i]);
			}
			dp[i] = max;
		}

		System.out.println(dp[N]);
	}

}