#include <stdio.h>

int main(){
	int n;
	double sum,val;
	while(scanf("%d",&n)!=EOF){
		int res = 0;
		sum = 0;
		while(n--){
			scanf("%lf",&val);
			if(val>0){
				sum += val/2;
			}else{
				sum += val;
			}
			if(sum<0){
				res++;
			}
		}
		printf("%d\n",res);
	}
}