#define Z(C,D,P)for(R=0,l=1,h=N;l<h;C){for(;l<h;D)if(v[l]+v[h]P 0)break;if(l==h)break;};l=!printf("%d ",R);
c(int*a,int*b){return*a-*b;}v['abc'],N,R,l;main(h){for(;~scanf("%d",&v[N++]););qsort(v+1,N-=2,4,c);Z(R++|l++|h--,h--,<)Z(R++|l++|h--,l++,>)Z((v[l]+v[h]==0&&R++,h--,l++),h--,<=)}