#include <iostream>
#include <cassert>
#include <climits>
#include <bitset>
#include <stack>
#include <queue>
#include <iomanip>
#include <limits>
#include <string>
#include <cmath>
#include <set>
#include <map>
#include <math.h>
#include <algorithm>
#include <vector>
#include <string.h>
#include <tuple>
#include <time.h>
#include <random>

using namespace std;

typedef long long ll;
typedef pair<ll,ll> P;

long long int INF = 3e18;
double Pi = 3.1415926535897932384626;

vector<ll> G[500005];
//vector<P> tree[500010];
priority_queue <ll> pql;
priority_queue <P> pqp;
//big priority queue
priority_queue <ll,vector<ll>,greater<ll> > pqls;
priority_queue <P,vector<P>,greater<P> > pqps;
//small priority queue
//top pop

int dx[8]={1,0,-1,0,1,1,-1,-1};
int dy[8]={0,1,0,-1,1,-1,-1,1};
char dir[] = "DRUL";
//ll bit[500005];
//↓,→,↑,←


#define p(x) cout<<x<<endl;
#define el cout<<endl;
#define pe(x) cout<<(x)<<" ";
#define ps(x) cout<<fixed<<setprecision(25)<<x<<endl;
#define pu(x) cout<<(x);
#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define deba(x) cout<< #x << " = " << x <<endl


ll mod = 1000000007;
ll rui(ll number1,ll number2){

    if(number2 == 0){
        return 1;
    }else{
        ll number3 = rui(number1,number2 / 2);
        number3 *= number3;
        number3 %= mod;
        if(number2%2==1){
            number3 *= number1;
            number3 %= mod;
        }
        return number3;
    }
}
ll gcd(ll number1,ll number2){

    if(number1 > number2){
        swap(number1,number2);
    }
    if(number1 == 0 || number1 == number2){
        return number2;
    }else{
        return gcd(number2 % number1,number1);
    }
}
void YES(bool condition){

    if(condition){
        p("YES");
    }else{
        p("NO");
    }
    return;
}
void Yes(bool condition){

    if(condition){
        p("Yes");
    }else{
        p("No");
    }
    return;
}

/*
void c3_init(){
    fact[0] = rfact[0] = 1;
    for(ll i=1; i<=800000; i++){
        fact[i] = (fact[i-1]*i) % mod;
    }
	rfact[800000] = rui(fact[800000],mod - 2);
	for(ll i=800000; i>=1; i--){
	   rfact[i-1] = rfact[i] * i;
	   rfact[i-1] %= mod;
	}
	return;}
ll c3(ll n,ll r){
    return (((fact[n] * rfact[r]) % mod) * rfact[n-r]) % mod;}
*/

ll n,m,num,sum,ans,a,b,c,d,e,g,h,w,i,j,k,q,l,r,idx;
ll x[500005],y[500005],z[500005];
char s[2005][2005];

ll leftdp[2005][2005];
ll rightdp[2005][2005];
ll updp[2005][2005];
ll downdp[2005][2005];
//bool used[500005];
bool flag,dame;

void count(){
    for(i=0;i<h;i++){
        a = 0;
        for(j=0;j<w;j++){
            if(s[i][j] == '.')a++;
            else a = 0;
            leftdp[i][j] = a;
        }
    }
    for(i=0;i<h;i++){
        a = 0;
        for(j=w-1;j>=0;j--){
            if(s[i][j] == '.')a++;
            else a = 0;
            rightdp[i][j] = a;
        }
    }
    for(j=0;j<w;j++){
        a = 0;
        for(i=0;i<h;i++){
            if(s[i][j] == '.')a++;
            else a = 0;
            updp[i][j] = a;
        }
    }
    for(j=0;j<w;j++){
        a = 0;
        for(i=h-1;i>=0;i--){
            if(s[i][j] == '.')a++;
            else a = 0;
            downdp[i][j] = a;
        }
    }
}

int main(){
	cin >> h >> w;
    for(i=0;i<h;i++){
        cin >> s[i];
    }
    count();
    ans = -1;
    for(i=0;i<h;i++){
        for(j=0;j<w;j++){
            num = leftdp[i][j] + rightdp[i][j] + updp[i][j] + downdp[i][j] - 3;

            ans = max(ans,num);
        }
    }
    p(ans);

	return 0;
}

Measured memory_bytes: 145024