#include<stdio.h>

int main() {
	int n;
	float t;
	float l;
	int q;

	l = 0;
	q = 0;
	while(scanf("%d", &n)!=EOF) {
		while(n--) {
			scanf("%f", &t);
			t = (t>0)?t/2:t;
			l += t;
			if (l<0) {
				q++;
			}
		}
		printf("%d\n", q);
		l = 0;
		q = 0;
	}

	return 0;
}