131. Hardwood floor time limit per test: 0.25 sec.
The banquet hall of Computer Scientists' Palace has a rectangular form of the size M x N (1<=M<=9, 1<=N<=9). It is necessary to lay hardwood floors in the hall. There are wood pieces of two forms:
Input The first line contains natural number M. The second line contains a natural number N.
Output First line should contain the number X, or 0 if there are no solutions.
Sample Input 2 3
Sample Output 5  

Name 
