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