#include <stdio.h>
int main(void){
	int n,i;
	double a[10000];
	while(scanf("%d",&n)!=EOF){
		int sum1=0;
		double sum2=0;
		for(i=0;i<n;i++){
			scanf("%lf",&a[i]);
		}
		for(i=0;i<n;i++){
			if(a[i]>0)
			  sum2=sum2+a[i]/2;
			else
			  sum2=sum2+a[i];
			if(sum2<0)
			  sum1=sum1+1;
		}
		printf("%d\n",sum1);
		
	}
return 0;
}