#include<stdio.h>
int main (void){
	int n,i;
	int a,sum=0;
    while(scanf("%d",&n)!=EOF){
    	int w=0;
    	sum=0;
    	for(i=1;i<=n;i++){
    		scanf("%d",&a);
    		a=(a>=0)?a/2:a;
			sum=sum+a;
			w=(sum<0)?++w:w;
		}
			printf("%d\n",w);
	}
	return 0;
}