var n,i,j:longint;
f:text;
begin
assign(f,'tije.in');reset(f);
readln(f,n);
close(f);
i:=1;
assign(f,'tije.out');rewrite(f);
while i<>n+1 do
      begin
      writeln(f,i,' ',n+1);
      writeln(f,i,' ',n+1);
      inc(i);
      end;
for i:=n downto 1 do
    for j:=1 to n do
        if j<>i then writeln(f,n+1,' ',j);
close(f);
end.