var x,y:array[1..500500] of longint;
    n2,n,k:longint;
    x2,y2:array[1..1000] of longint;
    nr:int64;
    i,j:longint;
    f,g:text;

begin
  assign(f,'trapez.in');reset(f);
  assign(g,'trapez.out');rewrite(g);
  read(f,n2);
  for i:=1 to n2 do
    read(f,x2[i],y2[i]);
  n:=0;
  for i:=1 to n2-1 do
    for j:=i+1 to n2 do
      begin
        inc(n);
        x[n]:=x2[i]-x2[j];
        y[n]:=y2[i]-y2[j];
      end;
  nr:=0;
  for i:=1 to n-1 do
    begin
      k:=0;
      for j:=i+1 to n do
        if x[i]*y[j]=x[j]*y[i] then inc(k);
      nr:=nr+k*(k+1) div 2;
    end;
  writeln(g,nr);
  close(f);
  close(g);
end.