var x,y:array[1..1500] of real;
    z:array[1..1000] of real;
    i,j,k,n,p:longint;
    m:real;

procedure sort;
    var i:integer;
        ok:boolean;
        t:real;
         begin
     repeat
     ok:=FALSE;
     for i:=1 to k-1 do
      if z[i]>z[i+1] then begin
                  t:=z[i+1];
                  z[i+1]:=z[i];
                  z[i]:=t;
                  ok:=TRUE;
                  end;
    until ok=FALSE;
    end;

    begin
  readln(n);
  for i:=1 to n do read(x[i],y[i]);

  for i:=1 to n do
   for j:=i+1 to n do begin
     inc(k);
     z[k]:=sqrt(sqr(x[i]-x[j])+sqr(y[i]-y[j]));
     end;
     sort;
     m:=z[1]
     for i:=2 to k do if z[i]=m then inc(p)
                  else begin
                   m:=z[i];
                   x:=(p-2)*(p-1)*p div 6;
       end;