Industrious bees#70

Industrious bees

1 second
64 megabytes
Very easy

Bees are known as some of the most industrious creatures in the world. In the beehive, only certain bees are responsible for guarding the collected honey. Our hive uses the following rules:

Each bee's working area depends on its grade:

Cells are numbered starting from the bottom-left cell, then continuing row by row in the direction along the bottom-left edge (see figure).

For inspection, the bee moves from cell to cell , each time choosing a different path in order to visit as many distinct cells as possible. At every step, the bee can move in one of three directions: up, up-right, or down-right. In how many ways can a bee of grade get from cell to cell ?

Input

The input contains a single line with two integers: (the bee's grade) and (the number of the target cell), where 1 \le K \le 14.

Output

Output a single integer — the number of possible ways.

Examples

Example 1

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