Find Blank Subgrids

You are given a grid of size \(n \times m\). Your task is to find all possible rectangular subgrids. A subgrid is defined by two pairs of coordinates: the top-left corner \((r_1, c_1)\) and the bottom-right corner \((r_2, c_2)\), where \(0 \le r_1 \le r_2 < n\) and \(0 \le c_1 \le c_2 < m\).

Your program should output each subgrid coordinate on a separate line in the following format:

(r1, c1) (r2, c2)

For example, for a \(3 \times 3\) grid, the subgrid (0, 0) (1, 1) represents the rectangular block spanning from row 0, column 0 to row 1, column 1.

The output order should follow a natural lexicographical order: first by \(r_1\), then \(c_1\), then \(r_2\), and finally \(c_2\).

inputFormat

Input is read from standard input. The first line contains two integers \(n\) and \(m\) separated by a space, representing the number of rows and columns respectively.

outputFormat

Output all possible subgrids on separate lines. Each line must display two coordinate pairs in the format: (r1, c1) (r2, c2).

## sample

1 1

(0, 0) (0, 0)

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