#include<stdio.h>
int main(){
	int n,i,ans;
	double t,a;
	while(scanf("%d",&n)!=EOF){
		ans=0;
		t=0;
		for(i=0;i<n;i++){
			scanf("%lf",&a);
			{if(a>0)
			{t=t+a/2;}
			else
			{t=t+a;}}
			if(t<0)
				ans++;
			}
			
			printf("%d\n",ans);
	}
return 0;
}