uses crt;
type
  m=record
   x,y:integer;
  end;
var
 h,g:text;
 i,n,j,k,l,u:integer;
 a:array[1..100] of m;
 function f(x1,y1,x2,y2:integer):real;
  begin
    if (y2-y1=0) or (x2-x1=0) then f:=0 else
     f:=(y2-y1)/(x2-x1)
  end;
begin
 assign(h,'trapez.in'); reset(h);
 assign(g,'trapez.out'); rewrite(g);
 readln(h, n);
 for i:=1 to n do begin
  read(a[i].x,a[i].y);
  readln;
 end;
 for i:=1 to n do
  for j:=i+1 to n do
   for k:=j+1 to n do
    for l:=k+1 to n do
     if ((f(a[i].x,a[i].y,a[j].x,a[j].y)=f(a[k].x,a[k].y,a[l].x,a[l].y))and
      (f(a[j].x,a[j].y,a[l].x,a[l].y)<>f(a[i].x,a[i].y,a[k].x,a[k].y))) or
      ((f(a[j].x,a[j].y,a[l].x,a[l].y)=f(a[i].x,a[i].y,a[k].x,a[k].y))and
      (f(a[i].x,a[i].y,a[j].x,a[j].y)<>f(a[k].x,a[k].y,a[l].x,a[l].y)))
      then u:=u+1;
 writeln(g,u);
 close(h);
 close(g);
end.