Hotel rooms

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?

Input

Two positive integers $n$ and $m(n,m\le 10^6)$.

Output

Print the maximum number of guests that all the hotel standard rooms can accommodate.

Examples