You have an *n* × *m* board.
In how many mays can you cover it with 1 × 2 pieces?

**Input**

Input consists of *n* and *m*.
Assume 2 ≤ *nm* ≤ 40, and that *nm* is even.

**Output**

Print in lexicographical order all the ways to cover the board. To distinguish the pieces, the two cells of the same piece must have the same digit, and two adjacent pieces must have different digits. Apart from that, digits should be as small as possible. (See the sample output 3.) Print a blank line after every solution.

Public test cases

**Input**

1 2

**Output**

00

**Input**

2 2

**Output**

00 11 01 01

**Input**

2 4

**Output**

0010 2210 0011 1100 0100 0122 0101 0101 0110 0220

Information

- Author
- Salvador Roura
- Language
- English
- Official solutions
- C++
- User solutions
- C++