class Sudoku_Topology_Initial(
    ):
    def Topology_Initial(self):
        initial=set()
        for r in range(self.M):
            initial.add(r+1)

        #Starting topology
        topology=[]
        for r in range(self.M):
            topology.append([])

            for s in range(self.M):
                element=self.S[r][s]
                if (self.S[r][s]==0):
                    element=set(initial)

                topology[r].append(element)
                
        self.Topology_Eliminate(topology)
        
        return topology