#include <iostream>
#include <vector>
#include <cstdio>
#include <queue>
#include <algorithm>
#include <functional>
#include <string>
#include <queue>
#include <cmath>
#include <iomanip>
#include <map>
#include <set>
#include <deque>
#include <stack>
#include <random>
#include <unordered_map>
#include <unordered_set>
#define ll long long
#define fr(i,k,N) for(ll i=k; i<N;i++)
#define rep(i,N) for(ll i=0; i<N;i++)
#define ALL(v) v.begin(),v.end()
#define mp make_pair
using namespace std;
template <class X> void pr(X test){cout<<test<<endl;}
template <class X> void prr(X test){for(auto it:test){cout<<it<<endl;}}
template <class X> void prrr(X test){int f=0;for(auto it:test){cout<<(f++!=0?" ":"")<<it;}cout<<endl;}
template<typename X>
istream&operator>>(istream&i,vector<X>&v){for(X&x:v)i>>x;return i;}

class UF { // union find from https://github.com/kartikkukreja/blog-codes (MIT)
    // [usage]
    // auto uf = new UF(n);
    // uf->merge(l, r); // 0 <= l, r <= n-1
    // ...
public:
    int *id; // inner id
    int cnt; // number of all vartices
    int *sz; // sz[i] means size of i's set
    UF(int N)   {
        cnt = N;
        id = new int[N];
        sz = new int[N];
        for(int i=0; i<N; i++) {
            id[i] = i;
            sz[i] = 1;
        }
    }
    ~UF() {
        delete [] id;
        delete [] sz;
    }
    int find(int p) {
        int root = p;
        while (root != id[root]) root = id[root];
        while (p != root) {
            int newp = id[p];
            id[p] = root;
            p = newp;
        }
        return root;
    }
    void merge(int x, int y) {
        int i = find(x);
        int j = find(y);
        if (i == j) return;
        
        if (sz[i] < sz[j]) {
            id[i] = j;
            sz[j] += sz[i];
        } else {
            id[j] = i;
            sz[i] += sz[j];
        }
        cnt--;
    }
    bool connected(int x, int y) {
        return find(x) == find(y);
    }
    int count() {
        return cnt;
    }
};

// return sorted 約数s 1 <= x <= n
vector<ll> divv(ll n) {
  vector<ll> v;
  for(ll i = 1; i*i <= n; i++) {
    if(n%i == 0) {
      v.push_back(i);
      if(i*i != n) v.push_back(n/i);
    }
  }
  sort(ALL(v));
  return v;
}

int main() {
    int h,w;
    cin>>h>>w;
    vector<string> v(h);
    cin>>v;
    int u[2001][2001],d[2001][2001],l[2001][2001],r[2001][2001];
    int score = 0;

    rep(i, h) rep(j, w){

        auto c = v[i][j];
        if(c == '.') {
            if(i == 0) u[i][j] = 0;
            else u[i][j] = u[i-1][j] + 1;

            r[i][j] = 0;
            if(j == 0) {fr(k, j+1, w) if(v[i][k] == '.') r[i][j]++; else break;}
            else r[i][j] = r[i][j-1] - 1;
            
            if(j == 0) l[i][j] = 0;
            else l[i][j] = l[i][j-1] + 1;

            d[i][j] = 0;
            if(i == 0) {fr(k, i+1, h) if(v[k][j] == '.') d[i][j]++; else break;}
            else d[i][j] = d[i-1][j] - 1;
            
            score = max(score, u[i][j]+d[i][j]+l[i][j]+r[i][j]+1);
        } else {
            u[i][j]=-1;
            l[i][j]=-1;
            d[i][j]=0;
            fr(k, i+1, h) if(v[k][j] == '.') d[i][j]++; else break;
            r[i][j]=0;
            fr(k, j+1, w) if(v[i][k] == '.') r[i][j]++; else break;
        }
    }
        
    pr(score);

    
    return 0;
}


Measured memory_bytes: 68864