#define f(P,Q,R)for(l=0,r=~n;l<r;P)a[l]Q-a[r]?s++,R:0;s=!printf("%d ",s);
a[1<<18],s,r;main(n,l){for(;~scanf("%d",a-n--););qsort(a,-++n,4,"\x8b\7+\6\xc3");f(r--,<,l++)f(l++,>,r--)f(a[l]+a[r]<=0?r-=a[l++]==-a[r]:r--,==,0)}