#include <bits/stdc++.h>

using namespace std;

#define int long long
#define FOR(i, a, b) for(ll i = (a); i < (b); ++i)
#define FORR(i, a, b) for(ll i = (a); i > (b); --i)
#define REP(i, n) for(ll i = 0; i < (n); ++i)
#define REPR(i, n) for(ll i = n; i >= 0; i--)
#define FOREACH(x, a) for(auto &(x) : (a))
#define VECCIN(x)                                                              \
    for(auto &youso_ : (x)) cin >> youso_
#define mp make_pair
#define bitcnt __builtin_popcount
#define SZ(x) ((ll)(x).size())
#define fi first
#define se second
#define All(a) (a).begin(), (a).end()
template <typename T = long long> inline T IN() {
    T x;
    cin >> x;
    return (x);
}
inline void CIN() {}
template <class Head, class... Tail>
inline void CIN(Head &&head, Tail &&... tail) {
    cin >> head;
    CIN(move(tail)...);
}
#define CINT(...)                                                              \
    int __VA_ARGS__;                                                           \
    CIN(__VA_ARGS__)
#define LCIN(...)                                                              \
    ll __VA_ARGS__;                                                            \
    CIN(__VA_ARGS__)
#define SCIN(...)                                                              \
    string __VA_ARGS__;                                                        \
    CIN(__VA_ARGS__)
#define Yes(a) cout << (a ? "Yes" : "No") << "\n"
#define YES(a) cout << (a ? "YES" : "NO") << "\n"
#define Printv(v)                                                              \
    {                                                                          \
        FOREACH(x, v) { cout << x << " "; }                                    \
        cout << "\n";                                                          \
    }
template <typename T = string> inline void eputs(T s) {
    cout << s << "\n";
    exit(0);
}
template <typename A, size_t N, typename T>
void Fill(A (&array)[N], const T &val) {
    std::fill((T *)array, (T *)(array + N), val);
}

typedef long long ll;
typedef unsigned long long ul;
typedef vector<ll> VL;
typedef pair<ll, ll> PL;
typedef priority_queue<ll> PQ;
typedef priority_queue<ll, VL, greater<ll>> PQG;

const int INF = 1e9;
const int MOD = 1e9 + 7;
// const int MOD = 998244353;
const ll LINF = 1e18 + 1;
const ll dx[] = {1, -1, 0, 0};
const ll dy[] = {0, 0, 1, -1};

ll H, W;
vector<string> S;
vector<VL> l, r, u, d;

signed main() {
    cin >> H >> W;
    REP(i, H) S.emplace_back(IN<string>());
    l.resize(H, VL(W, 0));
    r.resize(H, VL(W, 0));
    u.resize(H, VL(W, 0));
    d.resize(H, VL(W, 0));
    REP(i, H) {
        if(S[i][0] == '.') l[i][0] = 1;
        REP(j, W - 1) {
            if(S[i][j + 1] == '.') l[i][j + 1] = l[i][j] + 1;
        }
    }
    REP(i, H) {
        if(S[i][W - 1] == '.') r[i][W - 1] = 1;
        REPR(j, W - 2) {
            if(S[i][j] == '.') r[i][j] = r[i][j + 1] + 1;
        }
    }
    REP(i, W) {
        if(S[0][i] == '.') u[0][i] = 1;
        REP(j, H - 1) {
            if(S[j + 1][i] == '.') u[j + 1][i] = u[j][i] + 1;
        }
    }
    REP(i, W) {
        if(S[H - 1][i] == '.') d[H - 1][i] = 1;
        REPR(j, H - 2) {
            if(S[j][i] == '.') d[j][i] = d[j + 1][i] + 1;
        }
    }
    ll ans = 0;
    REP(i, H) REP(j, W) {
        ans = max(ans, l[i][j] + r[i][j] + u[i][j] + d[i][j] - 3);
    }
    cout << ans << "\n";
}


Measured memory_bytes: 129664