#include<stdio.h>
FILE *f,*g;
long n,i,o,nr,j,m,x[1001],y[1001];
float z,panta[500000];
int main()
{ f=fopen("trapez.in","r"); g=fopen("trapez.out","w");
  fscanf(f,"%d",&n); for(i=1;i<=n;i++) fscanf(f,"%ld%ld",&x[i],&y[i]);
  m=0;
  for(i=1;i<n;i++)
   for(j=i+1;j<=n;j++)
    { m++;
      if(x[i]!=x[j]) panta[m]=float((y[j]-y[i]))/float((x[j]-x[i]));
      else panta[m]=3.485924;
    }
  for(i=1;i<m;i++)
   for(j=i+1;j<=m;j++)
    if(panta[i]==panta[j]) nr++;
  fprintf(g,"%ld",nr);
  fclose(g);
  return 0;
}