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

			if(sum<0){
				c++;
			}
		}
		printf("%d\n",c);
	}
	return 0;
}