#include <stdio.h>

int main(){
	int T;
		int lucky,n;
		int ans,total;
		while(scanf("%d",&n)!=EOF){
			total=0;
			ans=0;
			while(n--){
				scanf("%d",&lucky);
				if(lucky>0){
					lucky=lucky/2;
					total+=lucky;
				}
				else{
					total+=lucky;
				}
			if(total<0)
				ans+=1;
			
		}
			printf("%d\n",ans);
		}
	return 0;
}