#include<stdio.h> 
int main() {
    int a,b,c,n; 
    while(scanf("%d",&n)!=EOF) {
        a=0,b=0; 
        while(n--) { 
            scanf("%d",&c);
            a+=c<0?c:c/2; 
            b+=a<0?1:0;
            } 
            printf("%d\n",b);
            }
            return 0;}