Problems
Dominoes
Dominoes
Given a rectangular board m × n. Find the number of ways to pave her dominoes - rectangles of size 1 × 2 cell.
Input data
Two numbers m and n (1 ≤ m, n ≤ 10) are given on a line.
Output data
Print the number of ways to pave the board with dominoes of given size.
Examples
Input example #1
1 1
Output example #1
0
Input example #2
2 3
Output example #2
3