import java.io.*;
import java.util.*;

public class Main {
  private static int solve(int h, int w, boolean[][] empty) {
    int[][] leftCount = new int[h + 2][w + 2];
    int[][] rightCount = new int[h + 2][w + 2];
    int[][] upCount = new int[h + 2][w + 2];
    int[][] downCount = new int[h + 2][w + 2];
    
    for (int i = 1; i <= h; i++) {
      for (int j = 1; j <= w; j++) {
        if (empty[i][j]) {
          leftCount[i][j] = leftCount[i][j - 1] + 1;
          upCount[i][j] = upCount[i - 1][j] + 1;
        }
      }
    }
    
    for (int i = h; i >= 1; i--) {
      for (int j = w; j >= 1; j--) {
        if (empty[i][j]) {
          rightCount[i][j] = rightCount[i][j + 1] + 1;
          downCount[i][j] = downCount[i + 1][j] + 1;
        }
      }
    }
    
    int maxArea = 0;
    for (int i = 1; i <= h; i++) {
      for (int j = 1; j <= w; j++) {
        if (empty[i][j]) {
          maxArea = Math.max(maxArea, leftCount[i][j] + rightCount[i][j] + upCount[i][j] + downCount[i][j] - 3);
        }
      }
    }
    return maxArea;
  }
  
  private static void execute(ContestReader reader, PrintWriter out) {
    int h = reader.nextInt();
    int w = reader.nextInt();
    
    boolean[][] empty = new boolean[h + 2][w + 2];
    for (int i = 1; i <= h; i++) {
      char[] line = reader.next().toCharArray();
      for (int j = 1; j <= w; j++) {
        empty[i][j] = line[j - 1] == '.';
      }
    }
    
    out.println(solve(h, w, empty));
  }
  
  public static void main(String[] args) {
    ContestReader reader = new ContestReader(System.in);
    PrintWriter out = new PrintWriter(System.out);
    execute(reader, out);
    out.flush();
  }
}

class ContestReader {
  private BufferedReader reader;
  private StringTokenizer tokenizer;
  
  ContestReader(InputStream in) {
    reader = new BufferedReader(new InputStreamReader(in));
  }
  
  public String next() {
    while (tokenizer == null || !tokenizer.hasMoreTokens()) {
      try {
        tokenizer = new java.util.StringTokenizer(reader.readLine());
      } catch (Exception e) {
        throw new RuntimeException(e);
      }
    }
    return tokenizer.nextToken();
  }
  
  public int nextInt() {
    return Integer.parseInt(next());
  }
  
  public long nextLong() {
    return Long.parseLong(next());
  }
  
  public double nextDouble() {
    return Double.parseDouble(next());
  }
  
  public int[] nextIntArray(int n) {
    int[] array = new int[n];
    for (int i = 0; i < n; i++) {
      array[i] = nextInt();
    }
    return array;
  }
  
  public long[] nextLongArray(int n) {
    long[] array = new long[n];
    for (int i = 0; i < n; i++) {
      array[i] = nextLong();
    }
    return array;
  }
}

class Algorithm {
  private static void swap(Object[] list, int a, int b) {
    Object tmp = list[a];
    list[a] = list[b];
    list[b] = tmp;
  }
  
  public static <T extends Comparable<? super T>> boolean nextPermutation(T[] ts) {
    int rightMostAscendingOrderIndex = ts.length - 2;
    while (rightMostAscendingOrderIndex >= 0 &&
        ts[rightMostAscendingOrderIndex].compareTo(ts[rightMostAscendingOrderIndex + 1]) >= 0) {
      rightMostAscendingOrderIndex--;
    }
    if (rightMostAscendingOrderIndex < 0) {
      return false;
    }
    
    int rightMostGreatorIndex = ts.length - 1;
    while (ts[rightMostAscendingOrderIndex].compareTo(ts[rightMostGreatorIndex]) >= 0) {
      rightMostGreatorIndex--;
    }
    
    swap(ts, rightMostAscendingOrderIndex, rightMostGreatorIndex);
    for (int i = 0; i < (ts.length - rightMostAscendingOrderIndex - 1) / 2; i++) {
      swap(ts, rightMostAscendingOrderIndex + 1 + i, ts.length - 1 - i);
    }
    return true;
  }
  
  public static void shuffle(int[] array) {
    Random random = new Random();
    int n = array.length;
    for (int i = 0; i < n; i++) {
      int randomIndex = i + random.nextInt(n - i);
      
      int temp = array[i];
      array[i] = array[randomIndex];
      array[randomIndex] = temp;
    }
  }
  
  public static void shuffle(long[] array) {
    Random random = new Random();
    int n = array.length;
    for (int i = 0; i < n; i++) {
      int randomIndex = i + random.nextInt(n - i);
      
      long temp = array[i];
      array[i] = array[randomIndex];
      array[randomIndex] = temp;
    }
  }
  
  public static void sort(int[] array) {
    shuffle(array);
    Arrays.sort(array);
  }
  
  public static void sort(long[] array) {
    shuffle(array);
    Arrays.sort(array);
  }
}



Measured memory_bytes: 109756