#include<stdio.h>
#include<math.h>
#include<stdlib.h>
#include<string.h>
int main(){
	int n,num,temp;
	float lucky;
	while(scanf("%d",&n)!=EOF){
		num = 0;
		lucky=0;
		while(n--){
			scanf("%d",&temp);
			if(temp<0){
				lucky += temp;
			}else{
				lucky += temp*0.5;
			}
			if(lucky<0){
				num++;
			}
		}
		printf("%d\n",num);
	}
}