A sorting method is called stable if two elements with the same value are interchanged at any time during the process.

Example: When sorting the list L = {27, 3₁, 9, 15, 3₂, 11}, in which the number 3 appears twice, a stable sorting method supplies the list L = {3₁, 3₂, 9, 11, 15, 27 }. a) Examine the stability of myergesort and heapsort sorting methods. Justify your answer. In the case of an unstable procedure, it is sufficient to specify a counterexample.