Program tije;
Var f:text;
    n,i,st,dr,j,jj:longint;
Begin
  assign(f,'tije.in');
  reset(f);
  readln(f,n);
  close(f);
  assign(f,'tije.out');
  rewrite(f);
  for i:=n downto 1 do Writeln(f,i,' ',n+1);
  st:=1;
  dr:=n;
  for i:=1 to n-1 do
     if i mod 2=1 then
       begin
        for j:=st to dr-2 do
           Writeln(f,dr,' ',j);
        for j:=1 to i do
           Writeln(f,dr-1,' ',dr);
        for j:=dr-2 downto st do
           begin
            for jj:=1 to i do
               Writeln(f,j,' ',j+1);
               Writeln(f,j,' ',dr);
           end;
        dec(dr);
       end
                  else
       begin
        for j:=dr downto st+2 do
           Writeln(f,st,' ',j);
        for j:=1 to i do
           Writeln(f,st+1,' ',st);
        for j:=st+2 to dr do
           begin
            for jj:=1 to i do
               Writeln(f,j,' ',j-1);
               Writeln(f,j,' ',st);
           end;
        inc(st);
       end;


  for i:=n downto 1 do Writeln(f,n+1,' ',(n+1) div 2);
  close(f);
End.