in this problem we are given a family of finite sets S1,.,Sm and a number k|F|.we call U = Ui=1to m Si universal set and denote its size n.

in this problem we are given a family of finite sets S1,...,Sm and a number k<|F|.we call U = Ui=1to m Si universal set and denote its size n.We are asked to find a subfamily F'c F of size k such that every element of U is contained in at least one set of the family F'.Note that MinSC in NP-complete.Design backtracking D&C algorithm for this problem,prove its correctness and estimate its run time.