#include<stdio.h>
#include<string.h>

int main() {
	int n;
	double a;
	while(scanf("%d",&n) != EOF) {
		int iTemp = 0;
		int iRet = 0;
		while(n--) {
			scanf("%lf",&a);
			if(a > 0) {
				iTemp = iTemp + a/2.0;
			}
			if(a<0) iTemp = iTemp + a;
			if(iTemp < 0) iRet++;
		}
		printf("%d\n",iRet);
	}
	return 0;
}