program p1;
var i,j,n,s:longint;
    f1,f2:text;
begin
assign(f1,'fractii.in'); reset(f1);
assign(f2,'fractii.out'); rewrite(f2);

  read(f1,n);
  for i:=1 to n do
   for j:=1 to n do
    if i>j then
    if (i mod j <> 0)or(i=1)or(j=1) then
                                     begin
                                      inc(s);
                                      writeln(f2,i,'-',j);
                                     end else
           else
            if (j mod i <> 0)or(i=1)or(j=1) then
                                             begin
                                              inc(s);
                                              writeln(f2,i,'-',j);
                                             end;
  write(f2,s);

close(f1); close(f2);
end.