// Arup Guha
// 3/5/2022
// Solution to 2021 SER D2 Problem: Overdraft

import java.util.*;

public class overdraft {
	
	public static void main(String[] args) {

		// Get # of numbers.
		Scanner stdin = new Scanner(System.in);
		int n = stdin.nextInt();
		
		// Read list keeping running sum and min of running sum.
		int min = 0, sum = 0;
		for (int i=0; i<n; i++) {
			sum += stdin.nextInt();
			min = Math.min(min, sum);
		}
		
		// Ta da!
		System.out.println(-min);
	}
}