import java.io.*;

public class Main{
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        String[] temp =reader.readLine().split(" ");
        int n = Integer.parseInt(temp[0]), m = Integer.parseInt(temp[1]);
        int[][] f = new int[n+1][m+1];
        int res = 0;
        for (int i = 1; i <=n; i++) {
            temp = reader.readLine().split(" ");
            for (int j = 1; j <=m; j++) {
                f[i][j] = Integer.parseInt(temp[j-1]);
                if (f[i][j] == 1){
                    f[i][j] = Math.min(Math.min(f[i-1][j], f[i][j-1]), f[i-1][j-1]) + 1;
                    res = Math.max(res, f[i][j]);
                }
            }
        }
        System.out.println(res*res);
    }
}