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

function pozitionare(st,dr:integer):integer;
var xst,xdr,aux:integer;
begin
  xst:=0;
  xdr:=-1;
  while st<dr do
    if a[st]<a[dr] then
      begin
        st:=st+xst;
        dr:=dr+xdr;
      end
    else
      begin
        aux:=a[st];
        a[st]:=a[dr];
        a[dr]:=aux;
        xst:=1-xst;
        xdr:=-1-xdr;
        st:=st+xst;
        dr:=dr+xdr;
      end;
  pozitionare:=st;
end;

procedure quick(st,dr:integer);
var p:integer;
begin
  p:=pozitionare(st,dr);
  if st<p-1 then quick(st,p-1);
  if p+1<dr then quick(p+1,dr);
end;

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);
        if (y2[i]-y2[j]>0) and (x2[i]-x2[j]>0)then
          a[n]:=trunc((x2[i]-x2[j])/(y2[i]-y2[j])*100)
        else
          if (y2[i]-y2[j]=0) then a[n]:=0
        else
          a[n]:=9000;
      end;
  quick(1,n);
  k:=0;
  for i:=2 to n do
    if a[i]=a[i-1] then inc(k)
                   else begin nr:=nr+k*(k+1) div 2;k:=0; end;
  writeln(g,nr);
  close(f);
  close(g);
end.