重贴
#include <stdio.h>
#include <stdlib.h>
int abs64(int a){
    if(a<0) return -a;else return a;
}
int cmp(const void *i,const void *j){
    return *((const int*)i)-*((const int*)j);
}
int numerate1[7800000],numerate2[7800000],a[4001],b[4001],c[4001],d[4001],tem;
int main(int argc, char *argv[])
{
    long index,i,j,k,m,n,counter=0,head,tail,ch,ct,c1,c2;
    scanf("%d",&n);
    for(i=0;i<n;i++) scanf("%d %d %d %d",&a[i],&b[i],&c[i],&d[i]);
    counter=0;
    index=0;
    for(i=0;i<n;i++){
        for(j=0;j<n;j++){
            numerate1[index++]=a[i]+b[j];
        }
    }
    index=0;
    for(i=0;i<n;i++){
        for(j=0;j<n;j++){
            numerate2[index++]=c[i]+d[j];
        }
    }
    qsort(numerate1,index,sizeof(int),cmp);
    qsort(numerate2,index,sizeof(int),cmp); 
    head=0;tail=index-1;
    while(head<index && tail>=0){
        c1=1;c2=1;
        if(numerate1[head]+numerate2[tail]==0) {
            ch=head;ct=tail;
            while(head<index && numerate1[ch]==numerate1[++head]) c1++;
            while(tail>=0 && numerate2[ct]==numerate2[--tail]) c2++;
            counter=counter+c1*c2;
        }
        else if(numerate1[head]<=0&&numerate2[tail]>=0){
            if(abs64(numerate1[head])<abs64(numerate2[tail])) tail--;
            else head++;
        }
        else if(numerate1[head]>=0&&numerate2[tail]<=0){
            if(abs64(numerate1[head])<abs64(numerate2[tail])) head++;
            else tail--;
        }
        else if(numerate1[head]<=0&&numerate2[tail]<=0){ head++;
        }
        else if(numerate1[head]>=0&&numerate2[tail]>=0){ tail--;
        }
    }
    printf("%ld\n",counter);
}