#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<string,int>;
using T = tuple<string,int,int>;

char g[2000][2000];
int H,W;

int dfs(int x, int y){
  int cnt = 1;
  for(int i = y-1; i >= 0; i--){
    if(g[x][i] == '#') break;
    cnt++;
  }
  for(int i = y+1; i < W; i++){
    if(g[x][i] == '#') break;
    cnt++;
  }
  for(int i = x-1; i >= 0; i--){
    if(g[i][y] == '#') break;
    cnt++;
  }
  for(int i = x+1; i < H; i++){
    if(g[i][y] == '#') break;
    cnt++;
  }
  return cnt;
}

int main(){
  cin >> H >> W;
  for(int i = 0; i < H; i++){
    for(int j = 0; j < W; j++){
      cin >> g[i][j];
    }
  }
  int ma = H+W-1;
  int ans = 0;
  for(int i = 0; i < H; i++){
    for(int j = 0; j < W; j++){
      if(g[i][j] == '#') continue;
      int temp = dfs(i,j);
      ans = max(ans, temp);
      if(ans == ma) break;
    }
  }
  cout << ans << endl;
  return 0;
}