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