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