var f,g:text;
n,i,j,l:byte;
begin
assign(f,'tije.in');
reset(f);
readln(f,n);
close(f);
assign(g,'tije.out');
rewrite(g);
for i:=n-1 downto 1 do
begin
for j:=1 to i do
writeln(g,1,' ',n+1);
for l:=1 to n do
  for j:=1 to i do
    writeln(g,l+1,' ',l);
end;
{for i:=n-1 downto 1 do
writeln(g,i,' ',n);
for i:=1 to n-1 do
for j:=n downto 1 do
writeln(g,n+1,' ',i); }
if n=1 then begin
      writeln(g,'1',' ','2');
      writeln(g,'2',' ','1');
      end;
close(g);
end.