#include <stdio.h>
#include <math.h>
using namespace std;
FILE*f=fopen("triang.in","r");
FILE*g=fopen("triang.out","w");

int i,j,k,s=0,n;
double a,b,c;
double dif(double x1,double y1,double x2,double y2){

return sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));


}
int main()
{
    double v[1501][2];

fscanf(f,"%d",&n);
   for(i=1;i<=n;i++) fscanf(f,"%lf%lf",&v[i][0],&v[i][1]);
   for(i=1;i<=n-2;i++)
    for(j=i+1;j<=n-1;j++)
   for(k=j+1;k<=n;k++){
 a=dif(v[i][0],v[i][1],v[j][0],v[j][1]);
 b=dif(v[k][0],v[k][1],v[j][0],v[j][1]);
 c=dif(v[i][0],v[i][1],v[k][0],v[k][1]);
 if((a-b<0.0001)&&(a-b>-0.0001)&&(c-b<0.0001)&&(c-b>-0.0001))s++,k=n;

   }

   fprintf(g,"%d",s);

   fclose(f);
   fclose(g);

    return 0;
}