#include <bits/stdc++.h>
using namespace std;

#define NDEBUG
#include <cassert>


typedef long long ll;
typedef long double Double;
typedef unsigned long long ull;
typedef pair<int,int> ii;
typedef pair<ll,ll> llll;
typedef pair<double,double> dd;

typedef vector<int> vi;
typedef vector<vector<int>> vvi;
typedef vector<ii> vii;
typedef vector<vector<ii>> vvii;
typedef vector<ll> vll;
typedef vector<string> vs;
typedef vector<double> vd;
typedef vector<long double> vD;

#define sz(a)  int((a).size())
#define pb  push_back
#define eb  emplace_back
#define FOR(var,from,to) for(int var=(from);var<=(to);++var)
#define rep(var,n)  for(int var=0;var<(n);++var)
#define rep1(var,n)  for(int var=1;var<=(n);++var)
#define repC2(vari,varj,n)  for(int vari=0;vari<(n)-1;++vari)for(int varj=vari+1;varj<(n);++varj)
#define ALL(c)  (c).begin(),(c).end()
#define RALL(c)  (c).rbegin(),(c).rend()
#define tr(i,c)  for(auto i=(c).begin(); i!=(c).end(); ++i)
#define found(s,e)  ((s).find(e)!=(s).end())
#define mset(arr,val)  memset(arr,val,sizeof(arr))
#define mid(x,y) ((x)+((y)-(x))/2)
#define IN(x,a,b) ((a)<=(x)&&(x)<=(b))
#define cons make_pair

#define PQ(T) priority_queue<T>
#define RPQ(T) priority_queue<T,vector<T>,greater<T>>

template<class T> inline void amin(T & a, T const & b) { a = min(a, b); }
template<class T> inline void amax(T & a, T const & b) { a = max(a, b); }

inline ll square(ll x) { return x * x; }
inline ll gcd(ll a, ll b) { while(a) swap(a, b%=a); return b; }
template <typename T>
inline T mod(T a, T b) { return ((a % b) + b) % b; }


const ll MOD=1000000007LL;

ll ADD(ll x, ll y) { return (x+y) % MOD; }
ll SUB(ll x, ll y) { return (x-y+MOD) % MOD; }
ll MUL(ll x, ll y) { return x*y % MOD; }
ll POW(ll x, ll e) { ll v=1; for(; e; x=MUL(x,x), e>>=1) if (e&1) v = MUL(v,x); return v; }
ll DIV(ll x, ll y) { /*assert(y%MOD!=0);*/ return MUL(x, POW(y, MOD-2)); }
ll solve(int H,int W,vs& s) {
    vvi left(H, vi(W, 0)), right(H, vi(W, 0));
    rep(r,H){
        int las = 0;
        for (int c=0; c<W; ++c) {
            if (s[r][c] == '#') {
                las = 0;
                continue;
            } else {
                left[r][c] = las;
                ++las;
            }
        }
        las = 0;
        for (int c=W-1; c>=0; --c) {
            if (s[r][c] == '#') {
                las = 0;
                continue;
            } else {
                right[r][c] = las;
                ++las;
            }
        }
    }
    vvi upper(W, vi(H, 0)), lower(W, vi(H, 0));
    rep(c,W){
        int las = 0;
        for (int r=0; r<H; ++r) {
            if (s[r][c] == '#') {
                las = 0;
                continue;
            } else {
                upper[c][r] = las;
                ++las;
            }
        }
        las = 0;
        for (int r=H-1; r>=0; --r) {
            if (s[r][c] == '#') {
                las = 0;
                continue;
            } else {
                lower[c][r] = las;
                ++las;
            }
        }
    }
    int ans = 0;
    rep(r,H) rep(c,W){
        if (s[r][c] == '#') continue;
        amax(ans, left[r][c] + right[r][c] + upper[c][r] + lower[c][r] + 1);
    }
    return ans;
}

int main() {
    int H,W; cin>>H>>W;
    vs s(H); rep(i,H) cin >> s[i];
    cout << solve(H,W,s) << endl;
    return 0;
}


Measured memory_bytes: 67200