Problem Setter: safayat jakir rifat

In  a dreamland, there is a road, which have some lanes. If there is n lanes in that road, they are marked by 1 to n. i-th lane is wider than (i-1)-th lane, so cars of i-th lane contain one more wheel from the previous lane. Every i-th lane can afford cars which have lowest number of wheels and number of wheels in cars are distinct. Car which have more wheels is bigger in size so it can take more passengers. Every lane contain one more car than the previous lane and a car can hold double number of passengers form its wheels.

Note: Minimum number of wheels in a car is 2.

Input Format

The only line of the input file contain n and x(1<=n,x<= 50000) denote number of lanes of that road and number of car in first lane.

Output Format

The only line of output contains the number of passengers.

Samples