#include<cstdio>
#include<cstring>
#include<string>
#include<algorithm>
#include<iostream>
#include<cmath>
#include<stdlib.h>
using namespace std;
const int maxn = 1e5+10;
const int inf = 0x3f3f3f3f;
int n;
double a;
int main(){
	while(scanf("%d",&n)!=EOF){
	double ans=0;
	int t=0;
	for(int i=1;i<=n;i++){
		scanf("%lf",&a);
		if(a>0)
		ans+=a/2;
		else{
			ans+=a;
		}
		if(ans<0)t++;
//			printf("%f\n",ans);
	}
	printf("%d\n",t);
	}
}