#include<stdio.h>
int main() {
	int n,count, a[1007];
	while (scanf("%d", &n) != EOF) {
		double sum = 0;
		count = 0;
		while (n--) {
			scanf("%d", &a[n]);
			if (a[n] < 0) {
				sum += a[n];
			}
			else if (a[n] >= 0) {
				sum += a[n] / 2.0;
			}
			if (sum < 0)
				count++;
		}
		printf("%d\n", count);
	}
}