#include<stdio.h>
int main(){
 int n,i;
 while(scanf("%d",&n)!=EOF){
     int qiu=0;
	 double luck=0,a;
	 for(i=0;i<n;i++){
		 scanf("%lf",&a);
		 if(a>0)
			 luck+=a/2;
		 if(a<0)
			 luck+=a;
		 if(luck<0)
			 qiu++;
	 }
	 printf("%d\n",qiu);
 }
}