#include <iostream>
#include <vector>
#include<list>
#include <algorithm>
#include <string>
#include <math.h>
#include<map>
#include <utility>

#include<queue>
using namespace std;
#define REP(i,k,n) for(int i=k;i<n;i++)
 
#define INF 1844674407370955161
typedef long long unsigned int ll;
#define SIZE_OF_ARRAY(array) (sizeof(array)/sizeof(array[0]))
#define MOD 1000000007

template<typename T>
int vector_finder(std::vector<T> vec, T number) {
  auto itr = std::find(vec.begin(), vec.end(), number);
  size_t index = std::distance( vec.begin(), itr );
  if (index != vec.size()) { // 発見できたとき
    return 1;
  }
  else { // 発見できなかったとき
    return 0;
  }
}

template<typename T>
T gcd(T a,T b){
	if(b>0){
		return gcd(b, a % b);
	}else{
		return a;
	}
}

template<typename T>
T lcm(T a,T b){
	T g = gcd(a, b);
	return a * b / g;
}

void clear( std::queue<pair<int,int> > &q )
{
   std::queue<pair<int,int> > empty;
   std::swap( q, empty );
}
bool IsPrime(int num)
{
    if (num < 2) return false;
    else if (num == 2) return true;
    else if (num % 2 == 0) return false; // 偶数はあらかじめ除く

    double sqrtNum = sqrt(num);
    for (int i = 3; i <= sqrtNum; i += 2)
    {
        if (num % i == 0)
        {
            // 素数ではない
            return false;
        }
    }

    // 素数である
    return true;
}
template<typename T>
std::vector<T> enum_div(T n)//nの約数を列挙
{
	std::vector<T> ret;
	for(T i=1 ; i*i<=n ; ++i)
	{
		if(n%i == 0)
		{
			ret.push_back(i);
			if(i!=1 && i*i!=n)
			{
				ret.push_back(n/i);
			}
		}
	}
	return ret;
}

int H, W;

int main()
{
  
  cin >> H >> W;
  string S[H];
  int s[H][W];
  
  REP(i, 0, H)
  {
    cin >> S[i];
    REP(j,0,W){
      if(S[i][j]=='#'){
        s[i][j] = 0;
      }else{
        s[i][j] = 1;
      }
    }
    
  }

  int up[H][W];
  int down[H][W];
  int right[H][W];
  int left[H][W];

  REP(i, 0, H)
  {
    REP(j,0,W){
      up[i][j] = 0;
      down[i][j] = 0;
      right[i][j] = 0;
      left[i][j] = 0;
    }
  }

  REP(i,0,W){
    REP(j,0,H){
      if(j==0){
        if(s[j][i]==0){
         up[j][i] = 0;
        }else{
          up[j][i] =1;
        }
      }else{
        if(s[j][i]==0){
          up[j][i] = 0;
        }else{
          up[j][i] += up[j - 1][i] + 1;
        }
      }
    }
    for (int j = H - 1; j >= 0;j--){
      if(j==H-1){
        if(s[j][i]==0){
        down[j][i] = 0;
        }else{
          down[j][i] =1;
        }
      }else{
        if(s[j][i]==0){
          down[j][i] = 0;
        }else{
          down[j][i] += down[j + 1][i] + 1;
        }
      }
    }
  }

  REP(i,0,H){
    REP(j,0,W){
      if(j==0){
        if(s[i][j]==0){
          left[i][j] = 0;
        }else{
          left[i][j] =1;
        }
      }else{
        if(s[i][j]==0){
          left[i][j] = 0;
        }else{
          left[i][j] += left[i][j-1] + 1;
        }
      }
    }
    for (int j = W - 1; j >= 0;j--){
      if(j==W-1){
        if(s[i][j]==0){
        right[i][j] = 0;
        }else{
          right[i][j] =1;
        }
      }else{
        if(s[i][j]==0){
          right[i][j] = 0;
        }else{
          right[i][j] += right[i][j+1] + 1;
        }
      }
    }
  }
  int ans = 0;
  
  REP(i, 0, H)
  {
    REP(j,0,W){
      if (S[i][j] !='#')
      {
        int tmp = up[i][j] + down[i][j] + left[i][j] + right[i][j]-3 ;
        ans = max(tmp, ans);
        
        
      }
    }
  }
  cout << ans << endl;

  return 0;
}

Measured memory_bytes: 82432