#include<iostream>
#include<algorithm>

using namespace std;

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