A hotel has n floors. The lobby, restaurant and gym are located on the first floor. The guestrooms are on 2-nd to n-th floors. There are m standard rooms on each floor. If each standard room can fit 3 guests, what is the maximum number of guests that all the standard rooms can accommodate?
Two positive integers n and m~(n, m \le 10^6).
Print the maximum number of guests that all the hotel standard rooms can accommodate.