package Notes;

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

public class HomePartyx2 {

public class Main {

public static void main(String[] args) throws IOException {

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

String[] dimensions = bf.readLine().split(" ");

int R = Integer.parseInt(dimensions[0]);

int C = Integer.parseInt(dimensions[1]);

char[][] apartment = new char[R][C];

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

String line = bf.readLine();

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

apartment[i][j] = line.charAt(j);

}

}

int maxPeople = 0;

int[] dx = {-1, 0, 1, 0};

int[] dy = {0, 1, 0, -1};

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

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

if (apartment[i][j] == '.') {

int perimeter = 0;

for (int k = 0; k < 4; k++) {

int ni = i + dx[k];

int nj = j + dy[k];

if (ni >= 0 && ni < R && nj >= 0 && nj < C && apartment[ni][nj] == '.') {

perimeter++;

}

}

maxPeople = Math.max(maxPeople, perimeter);

}

}

}

System.out.println(maxPeople-1);

}

}

}