#include<stdio.h>
int main(){
	int T,n,x,y,sum;
		while(scanf("%d",&T)!=EOF){
			sum=0;x=0;
			while(T--){
				scanf("%d",&n);
					y=0;
					if(n>0)
					{
						y=n/2;
					}
					else if(n<0)
						y=n;
					sum+=y;
					if(sum<0){
						x++;
					}
			}
			printf("%d\n",x);
		}


	return 0;
}