#include <stdio.h>
int main() {
	int n, num;
	double a, sum;
	while(~scanf("%d", &n)){
	  sum = num = 0;
	  while(n --) {
	  	scanf("%lf", &a);
	  	if(a > 0) {
	  	  sum += a/2;	
		}else {
		  sum += a;
		}
		
		if(sum < 0) {
		  num ++;
		}
	  }	
	  printf("%d\n", num);
	}
	return 0;
}