# include <stdio.h>
int main(void){
	int n,i,sum=0,icount=0;
	float card;
	while(scanf("%d",&n)!=EOF){
		icount=0;
		sum=0;
		for(i=0;i<n;i++){
			scanf("%f",&card);
			if(card>=0) sum+=card/2;
			else sum+=card;
			if(sum<0)icount++;
		}
		printf("%d\n",icount);
	}
}