Each of four machines is to be assigned to one of five possible locations. The objective is to assign the machines to locations that will minimize the materials handling cost. The machine–location costs are given in the following matrix. Find the optimal assignment.

A B C D E 1 26 20 22 21 25 2 35 31 33 40 26 3 15 18 23 16 25 4 31 34 33 30 M