The four variable function $\mathrm{f}$ is given in terms of min-terms as:
$$ f(A, B, C, D)=\sum m(2,3,8,10,11,12,14,15) . $$
Using the $K$-map minimize the function in the sum of products form. Also, given the realization using only two-input $\text{NAND}$ gates.
