o0o Harsh 4 o0o

There are 0nly 0ne way t0 ch00se $real numbers M and N$ such that when the $polynomial$ $5x^{4} + 4x^{3} + 3x^{2} + Mx + N$ when divided by the $polynomial$ $x^{2} + 1$ ; the $remainder$ is $0$ . If $M$ and $N$ assume these unique values ; then $M - N$ is $???$