program triang;
var f,g :text;
    x, y :array[0..500] of double;
    oldal1,oldal2,oldal3:double;
    n,i,j,k :integer;
    db: longint;

procedure beolvas;
var i:integer;
begin
  assign(f,'triang.in');reset(f);
  assign(g,'triang.out'); rewrite(g);
     read(f,n);
     for i:=1 to n do read(f,x[i],y[i]);
end;

BEGIN
  beolvas;
  db:=0;
  for i:=1 to n-2 do
      for j:=1 to n-1 do
          //if j<>i then
             for k:=1 to n do
                 //if (k<>i) and (k<>j) then
                    oldal1:=(x[i]-x[j])*(x[i]-x[j])+(y[i]-y[j])*(y[i]-y[j]);
                    oldal2:=(x[i]-x[k])*(x[i]-x[k])+(y[i]-y[k])*(y[i]-y[k]);
                    oldal3:=(x[j]-x[k])*(x[j]-x[k])+(y[j]-y[k])*(y[j]-y[k]);

  if (abs(oldal1-oldal2)<=0.001) and (abs(oldal1-oldal3)<=0.001) and (abs(oldal2-oldal3)<=0.001) then inc(db);

  write(g,db);
  close(f);
  close(g);
END.