#include <stdio.h>
int main(){
	int n,i,sum,count;
	while(scanf("%d",&n)!=EOF){
		int a[n];
		sum=0;count=0;
		for(i=1;i<=n;i++){
			scanf("%d",&a[i]);
			if(a[i]>=0){
				sum=sum+0.5*a[i];
			}else if(a[i]<0){
				sum=sum+a[i];
			}
			if(sum<0){
				count++;
			}
		}
		printf("%d\n",count);
	}
	return 0;
}