var n:longint;
 f,g:text;
 procedure diaconeasa_se_uita;
var i,j,k:longint;
begin
 for i:=n downto 2 do
 begin
 for j:=n-1 downto 1 do
 writeln(g,i,' ',n+1);
 for j:=n-i+1 downto 1 do
  writeln(g,i-1,' ',i);
 for j:=i-2 downto 1 do begin
     for k:=n-i downto 1 do
     writeln(g,j,' ',j+1);
     writeln(g,n+1,' ',j+1);
     writeln(g,j,' ',i);
 end;
 for j:=n-i+1 downto 1 do
 writeln(g,n+1,' ',1);
 end;
end;
 begin  
 assign(f,'tije.in');
 reset(f);
 read(f,n);
 close(f);
 assign(g,'tije.out');
 rewrite(g);
 diaconeasa_se_uita;
 close(g);
  end.