program tije;
var n,i,j,k:longint;
begin
  assign(input,'tije.in'); reset(input);
  assign(output,'tije.out'); rewrite(output);
  readln(n);
  for i:= n downto 2 do
    begin
      for j:= n-1 downto 1 do
        writeln(i,' ',n+1);
      for j:= n-i+1 downto 1 do
        writeln(i-1,' ',i);
      for j:= i-2 downto 1 do
        begin
          for k:= n-i downto 1 do
            writeln(j,' ',j+1);
          writeln(n+1,' ',j+1);
          writeln(j,' ',i);
        end;
      for j:= n-i+1 downto 1 do
        writeln(n+1,' ',1);
    end;
  close(input);
  close(output);
end.