#include<stdio.h>
int main(){
	int n,a[100000],count=0;
	double sum=0;
	while(scanf("%d",&n)!=EOF){
		count=0,sum=0;
		for(int i=0;i<n;i++){
			scanf("%d",&a[i]);
		}
		for(int j=0;j<n;j++){
			if(a[j]>0){
				sum+=(double)a[j]/2.0;
			}
			else{
				sum+=a[j];
			}
			if(sum<0)
				count++;}
		printf("%d\n",count);
	}
	return 0;}