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