#include<stdio.h>
int A[1000];
int main(){
	int n,i;
	while(scanf("%d",&n)!=EOF){
		int l=0,total=0;
		for(i=0;i<n;i++){
			scanf("%d",&A[i]);
			if(A[i]<0)
			l+=A[i];
			if(A[i]>=0)
			l+=A[i]/2;
			if(l<0)
			total+=1;		
		}
    	printf("%d\n",total);	

	}

	
	
	
	
	return 0;
}