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