> //pku2785 4 Values whose Sum is 0 hash＋o(n2)
> // hash
> #include<stdio.h>
> #include<memory.h>
> //#include<conio.h>
> int A[4005],B[4005],C[4005],D[4005];
> const int HSize=4000*4005*3;
> int HTable[4005*4000*3];
> int Visited[4005*4000*3];
> int Hash(int x)
> {
> 	int pos=x*10257-3;
> 	if(pos<0)
> 		pos*=-1;
> 	pos%=HSize;
> 	return pos; 
> }
> void ToHash(int x)
> {
> 	int pos,ii=1;
> 	for(pos=Hash(x);Visited[pos];pos+=ii++*3-1,pos%=HSize)
> 		;
> 	HTable[pos]=x;
> 	Visited[pos]=1;
> }
> 
> int Find(int x) 
> {
> 	int pos,ii=1;
> 	for(pos=Hash(x);Visited[pos];pos+=ii++*3-1,pos%=HSize)
> 		if(HTable[pos]==x)
> 			return 1;
> 	return 0;
> }
> 
> int main()
> {
> 	int n,rst=0;
> 	int ii,jj;
> 	for(;scanf("%d",&n)!=EOF;)
> 	{
> 	memset(Visited,0,sizeof(Visited));
> 	for(ii=0;ii<n;ii++)
> 	{
> 		scanf("%d%d%d%d",A+ii,B+ii,C+ii,D+ii);
> 	}
> 	for(ii=0;ii<n;ii++)
> 		for(jj=0;jj<n;jj++)
> 			ToHash(A[ii]+B[jj]);
> 	for(ii=0,rst=0;ii<n;ii++)
> 		for(jj=0;jj<n;jj++)
> 			if( Find(-1*(C[ii]+D[jj])) )
> 				rst++;
> 	printf("%d",rst);
> 	}
> //	getch();
> 	return 0;
> }