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