Find all solutions of the equation $4\sin x\cos x + 2\sin x -2\cos x -1 =0.$
The answer is $A+2k\pi$, $B+2k\pi$, $C+2k\pi$, and $D+2k\pi$ where $k$ is any integer and $0<A<B<C<D<2\pi$,
$A=$ ,
$B=$ ,
$C=$ ,
$D=$ .