Problem Description

There are some 2D lattice points on a plane.

The numbering of these points is like a 2D array: from top to bottom are rows $1$ to $n$, and from left to right are columns $1$ to $m$. Each point can be represented by its row number and column number.

Now a person stands at row $1$, column $1$, and wants to walk to row $n$, column $m$. They can only move right or down.

Note that if both the row number and the column number are even, you are not allowed to enter that cell.

How many different ways are there?

Input Format

One line contains two integers $n$ and $m$.

Output Format

Output one integer, the answer.

3 4

2

Hint

$1\le n,m\le30$.

Lanqiao Cup 2020 First Round Provincial Contest, Group A Problem G (Group B Problem H).

Translated by ChatGPT 5