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