Maximal Square Area

In a 01 matrix, find the axis-aligned squares consisting entirely of 1s and return the largest area.

This site has made the standard input and output explicit.

输入格式

The first line contains n m, followed by n 01 strings of length m. 1≤n,m≤300.

输出格式

Output one integer, the answer.

样例 1

输入：

4 5
10100
10111
11111
10010

输出：

4

样例 2

输入：

2 2
00
00

输出：

0

样例 3

输入：

2 3
111
111

输出：

4

样例说明

Example 1: there is an all-1 square of side 2 in the middle, so the largest area is 4. Example 2: everything is 0, so output 0; the original site's second 2×2 input was missing a row, which has been filled in. Example 3: there are only two rows, so the largest side is 2 and the area is 4.