Problem Description
A local area network (LAN) supplies networking capability to a group of computers in close proximity to each other such as in an office building, a school, or a home. A LAN is useful for sharing resources like files, printers, games or other applications. A LAN in turn often connects to other LANs, and to the Internet or other WAN.
In this contest, everybody is connecting with each others like the following figure.

The contest’s network was built as N rows and M columns, your computer locate at (0, 0) and the judger’s computer locate at (m-1, n-1) The code you submit would only transfer to up or right smoothly. It doesn’t matter if some accidents happened. Could you tell me how many ways from your computer to judger when a data wire was broken?

Input
There are multiple cases. Every case contains two integers in the first line, N, M (3<=N+M<=40). Second line contains four integers X1, Y1, X2, Y2 (0<=X1, X2<M, 0<=Y1, Y2<N, |X1+Y1-X2-Y2|=1), meaning the broken wire position.

Output
Print the answer in one line.

Sample Input
3 3
0 0 1 0

Sample Output
3