Factorize the following expressions into the product of two factors:

$$
x^{2}+2 x+1-y^{2}, \quad m^{2}-n^{2}-2 n p-p^{2}
$$
$$
x^{2}+2 x+1-y^{2}=(x+y+1)(x-y+1) \text { . }
$$

$$
m^{2}-n^{2}-2 n p-p^{2}=m^{2}-\left(n^{2}+2 n p+p^{2}\right)=(m+n+p)(m-n-p) .
$$