var     a:array[1..2,1..1000] of int64;
        n,i,j,k,l:integer;
        nr:longint;
        f,g:text;

begin
  assign(f,'trapez.in');
  assign(g,'trapez.out');
  reset(f);
  rewrite(g);
  readln(f,n);
  for i:=1 to n do
    readln(f,a[1,i],a[2,i]);
  for i:=1 to n-3 do
  for j:=i+1 to n-2 do
  for k:=j+1 to n-1 do
  for l:=k+1 to n do
    begin
      if (a[1,i]-a[1,j])*(a[2,k]-a[2,l])=(a[2,i]-a[2,j])*(a[1,k]-a[1,l])
        then inc(nr);
      if (a[1,i]-a[1,k])*(a[2,j]-a[2,l])=(a[2,i]-a[2,k])*(a[1,j]-a[1,l])
        then inc(nr);
      if (a[1,i]-a[1,l])*(a[2,k]-a[2,j])=(a[2,i]-a[2,l])*(a[1,k]-a[1,j])
        then inc(nr);
    end;
  writeln(g,nr);
  close(g);
end.