#include<stdio.h>
int main(){
int n,lucky,i,sum;
int flag;
while(scanf("%d",&n)!=EOF){
	sum=0;
	flag=0;
for(i=0;i<n;i++){
scanf("%d",&lucky);
if(lucky<0)
lucky=lucky;
else
lucky=0.5*lucky;
sum=sum+lucky;
if(sum<0)
flag++;
	}
printf("%d\n",flag);
}
}