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