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