#include<stdio.h>

int main(){
	int n;
	double a;
	float x = 0;
	int m = 0;
	while(scanf("%d",&n) != EOF){
		m = 0;
		x = 0;
		for(int i = 0;i < n;i++)
		{
			scanf("%lf",&a);
			if(a > 0){
				x = x + a / 2.0;
			}else{
				x = x + a;
			}
			if(x < 0){
				m ++;
			}
		}
		printf("%d\n",m);
	}
	return 0;
}