Description

A bee is crawling on the digital honeycomb shown in the figure below. It is known that the bee can only crawl from a cell with a smaller number to an adjacent cell with a larger number. Now, the question is: How many different crawling routes are there for the bee to go from cell M to cell N, where M < N?

Input Format

Input the values of M and N, where 1 ≤ M < N ≤ 1000.

Output Format

Output the number of possible crawling routes.

1 14

377

Source

CodesOnline