#include <iostream>
#include <iomanip>
#include <vector>
#include <valarray>
#include <map>
#include <set>
#include <list>
#include <queue>
#include <stack>
#include <bitset>
#include <utility>
#include <numeric>
#include <algorithm>
#include <functional>
#include <complex>
#include <string>
#include <sstream>
#include <array>

#include <cstdio>
#include <cstdlib>
#include <cctype>
#include <cstring>
#include <cassert>

#include <unordered_set>
#include <unordered_map>
#include <random>
#include <thread>
#include <chrono>

using namespace std;

#define all(c) c.begin(), c.end()
#define repeat(i, n) for (int i = 0; i < static_cast<int>(n); i++)
#define debug(x) #x << "=" << (x)

#ifdef DEBUG
#define dump(x) std::cerr << debug(x) << " (L:" << __LINE__ << ")" << std::endl
#else
#define dump(x)
#endif


template <typename T>
ostream &operator<<(ostream &os, const vector<T> &v)
{
    os << "{";
    for(auto it = v.begin(); it != v.end(); ++it) {
        if(it != v.begin())
            os << ",";
        os << *it;
    }
    return os << "}";
}

template <typename A, typename B>
ostream &operator<<(ostream &os, const pair<A, B> &v)
{
    os << "{";
    os << v.first << ", " << v.second;
    return os << "}";
}

// ---------------------------------------------------------------------------

using point = complex<double>;
using ll = int64_t;

// left
vector<vector<int>> solve(const vector<vector<bool>>& m)
{
    int h = m.size();
    int w = m[0].size();
    vector<vector<int>> ret(h, vector<int>(w));

    for (int r = 0; r < h; r++) {
        int k = -1;

        for (int c = 0; c < w; c++) {
            bool ok = m[r][c];
                
            if (ok) {
                int p = c - k - 1;
                ret[r][c] = p;
            } else {
                k = c;
            }
        }
    }

    return ret;
}

template<typename T>
vector<vector<T>> mirror(const vector<vector<T>>& v) {

    int h = v.size();
    int w = v[0].size();
    vector<vector<T>> ret(h, vector<T>(w));

    for (int i = 0; i < h; i++) {
        for (int j = 0; j < w; j++) {
            ret[i][w - j - 1] = v[i][j];
        }
    }

    return ret;
}

template <typename T>
vector<vector<T>> rotate(const vector<vector<T>>& v)
{

    int h = v.size();
    int w = v[0].size();
    vector<vector<T>> ret(w, vector<T>(h));

    for (int i = 0; i < h; i++) {
        for (int j = 0; j < w; j++) {
            ret[j][i] = v[i][j];
        }
    }

    return ret;
}


int my_main(int argc, char** argv)
{
    ios::sync_with_stdio(false);
    cin.tie(0);

    int h, w;
    cin >> h >> w;

    vector<vector<bool>> ok(h, vector<bool>(w));

    for (int i = 0; i < h; i++) {
        string s;
        cin >> s;

        for (int j = 0; j < w; j++) {
            ok[i][j] = s[j] == '.';
        }
    }

    auto s1 = solve(ok);
    auto s2 = mirror(solve(mirror(ok)));

    auto s3 = rotate(solve(rotate(ok)));
    auto s4 = rotate(mirror(solve(mirror(rotate(ok)))));

    int ret = 0;
    for (int i = 0; i < h; i++) {
        for (int j = 0; j < w; j++) {
            if (ok[i][j]) {
                int here = 1 + s1[i][j] + s2[i][j] + s3[i][j] + s4[i][j];
#if DEBUG
                cerr << i << " " << j << " " << s1[i][j] << " " << s2[i][j] << " " << s3[i][j] << " " << s4[i][j] << endl;
#endif
                ret = max(ret, here);
            }
        }
    }

    cout << ret << endl;
    return 0;
}





// ----------------------------------------------------------------------------
// Test driver

#ifdef DEBUG
#define MAY_RUN_TESTCASE
#endif

#ifdef MAY_RUN_TESTCASE
#include <fstream>

#if __has_include(<unistd.h>)
// Mac, Linux
#include <unistd.h>
#elif __has_include(<io.h>)
// Windows
#include <io.h>
#else
// Other?
#error "unistd.h or io.h not found"
#endif

bool test_file_exists(const std::string& str)
{
    std::ifstream fs(str);
    return fs.is_open();
}

#endif

int main(int argc, char** argv)
{
#ifndef MAY_RUN_TESTCASE
    return my_main(argc, argv);
#else
    if (argc == 1) {
        return my_main(argc, argv);
    }
    else if (argc == 2) {

        char* stdin_file = argv[1];
        freopen(stdin_file, "r", stdin);
        return my_main(argc, argv);

    } else if (argc == 5) {

        std::string stdin_file = argv[1];
        std::string expected_file = argv[2];
        std::string stdout_file = argv[3];
        std::string stderr_file = argv[4];

        if (!test_file_exists(stdin_file)) {
            std::cerr << stdin_file << " not found" << std::endl;
            return 3;
        }

        if (!test_file_exists(expected_file)) {
            std::cerr << expected_file << " not found" << std::endl;
            return 3;
        }

        int original_stdin = dup(fileno(stdin));
        int original_stdout = dup(fileno(stdout));
        int original_stderr = dup(fileno(stderr));

        freopen(stdin_file.c_str(), "r", stdin);
        freopen(stdout_file.c_str(), "w", stdout);
        freopen(stderr_file.c_str(), "w", stderr);

        int ret = my_main(argc, argv);

        fflush(stdout);
        fflush(stderr);

        dup2(original_stderr, fileno(stderr));
        dup2(original_stdout, fileno(stdout));
        dup2(original_stdin, fileno(stdin));

        if (ret != 0) {
            std::cerr << "main returns " << ret << std::endl;
            return ret;
        }

        std::ifstream inp(stdin_file);
        std::ifstream out(stdout_file);
        std::ifstream err(stderr_file);
        std::ifstream exp(expected_file);

        // Clear is needed if the file is empty.
        std::cout << "----- input -----" << std::endl;
        std::cout << inp.rdbuf() << std::endl;
        std::cout.clear();
        std::cout << "-----------------" << std::endl << std::endl;

        std::cout << "----- output ----" << std::endl;
        std::cout << out.rdbuf() << std::endl;
        std::cout.clear();
        std::cout << "-----------------" << std::endl << std::endl;

        std::cout << "---- expected ---" << std::endl;
        std::cout << exp.rdbuf() << std::endl;
        std::cout.clear();
        std::cout << "-----------------" << std::endl << std::endl;

        std::cout << "----- stderr ----" << std::endl;
        std::cout << err.rdbuf() << std::endl;
        std::cout.clear();
        std::cout << "-----------------" << std::endl;

        inp.seekg(0);
        out.seekg(0);
        exp.seekg(0);
        err.seekg(0);

        std::string output_str, expected_str;
        {
            std::stringstream output_ss;
            output_ss << out.rdbuf();
            output_str = output_ss.str();

            std::stringstream expected_ss;
            expected_ss << exp.rdbuf();
            expected_str = expected_ss.str();
        }

        // Remove trailing spaces
        output_str.erase(output_str.find_last_not_of(" \n\r\t") + 1);
        expected_str.erase(expected_str.find_last_not_of(" \n\r\t") + 1);

        if (output_str == expected_str)
            return 0;
        else
            return 1;
    }
    return 1;
#endif
}


Measured memory_bytes: 96384