package algorithm.baek.brute;

import algorithm.TestCase;

import java.io.*;

import java.text.ParseException;

import java.util.StringTokenizer;

/**

* https://www.acmicpc.net/problem/1051

* 숫자 정사각형

* 브루트포스

*/

public class NumSquare implements TestCase {

static int n, m;

static int[][] arr;

static int max = 1;

@Override

public void test() throws ParseException, IOException {

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

StringTokenizer st = new StringTokenizer(br.readLine());

n = Integer.parseInt(st.nextToken());

m = Integer.parseInt(st.nextToken());

arr = new int[n][m];

for (int i = 0; i < n; i++) {

String[] str = br.readLine().split("");

for (int j = 0; j < m; j++) {

arr[i][j] = Integer.parseInt(str[j]);

}

}

int min = Math.min(n, m);

for (int y = 0; y < n; y++) {

for (int x = 0; x < m - 1; x++) {

for (int size = 1; size < min; size++) {

if (y + size < n && x + size < m) {

if (arr[y][x] == arr[y][x + size]

&& arr[y][x] == arr[y + size][x]

&& arr[y][x] == arr[y + size][x + size]) {

max = Math.max(max, (size + 1) * (size + 1));

}

}

}

}

}

bw.write(max + "\n");

bw.flush();

bw.close();

}

}