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