Cut Board#8547
A rectangular board of size n \times m is divided into 1 \times 1 cells. consecutive cells are cut from the first row, starting from the top-left corner, and consecutive cells are cut from the last row, starting from the bottom-right corner. Can you fill all the remaining cells of the board using 2 \times 1 dominoes, so that no two dominoes overlap and none hang off the edge?
Write a program that, given four integers , , and , prints whether it is possible to cover the remaining board completely with dominoes. If possible, output one possible way to place the dominoes.
The input consists of a single line, containing four space-separated integers , , and (3 \leq n, m \leq 100, 1 \leq x, y < m).
If it is impossible to cover all the cells of the cut board with dominoes, print NO.
Otherwise, print YES in the first line, and in the second line print a single integer — the number of dominoes used.
Then, print that many lines, each containing four space-separated integers, denoting the location of a domino. Each line should specify x_1, y_1, x_2, y_2, with (x_1, y_1) and (x_2, y_2) being the two cells covered by one domino (rows are numbered from top to bottom, columns from left to right).
Each domino may be placed vertically or horizontally.
If there are multiple solutions, output any of them.
Example 1
Example 2