#include<stdio.h>
int main(){
	int j,i,n,a[1000],b[1000];
	while(scanf("%d",&n)!=EOF){
		int q=0;
		for(i=0;i<n;++i)
			scanf("%d",&a[i]);
		for(i=0;i<n;++i)
			if(a[i]>0)
				a[i]/=2;
		for(i=0;i<n;++i)
			b[i]=0;
		for(i=0;i<n;++i)
			for(j=0;j<=i;++j)
				b[i]+=a[j];
		for(i=0;i<n;++i)
			if(b[i]<0)
				q+=1;
		printf("%d\n",q);
	}
}