#include<stdio.h>

int main() {
	int t,n;
	double a;
	
	while(scanf("%d",&n) != EOF) {
		int qiuzhang=0;
		double luck=0;
	for(t=1;t<=n;t++) {
		scanf("%lf",&a);
		if(a>0) {
			luck=luck+a/2;
		}else {
			luck=luck+a;
		}
		if(luck<0) {
			qiuzhang=qiuzhang+1;
	    }

	  }
      printf("%d\n",qiuzhang);
    }
    return 0;
}