#include<bits/stdc++.h>
using namespace std;
#define int long long
#define rep(i,n) for(int i=0;i<(n);i++)
#define repr(i,n) for(int i=(n)-1;i>=0;i--)
#define repf(i,j,n) for(int i=(j);i<(n);i++)


signed main(){
	int h,w;cin>>h>>w;
	vector<string>s(h);
	for(auto&& u:s)cin>>u;

	vector<vector<int>>l(h+2,vector<int>(w+2,0));
	vector<vector<int>>r(h+2,vector<int>(w+2,0));
	vector<vector<int>>u(h+2,vector<int>(w+2,0));
	vector<vector<int>>d(h+2,vector<int>(w+2,0));

//  int l[h+2][w+2],r[h+2][w+2],u[h+2][w+2],d[h+2][w+2];



	for(int i=1;i<=h;i++)for(int j=1;j<=w;j++){
		if(s[i-1][j-1]=='.'){
		l[i][j]=l[i][j-1]+1;
		u[i][j]=u[i-1][j]+1;
		}
	}

  for(int i=h;i>=1;i--)for(int j=w;j>=1;j--){
		if(s[i-1][j-1]=='.'){
		r[i][j]=r[i][j+1]+1;
		d[i][j]=d[i+1][j]+1;
	}
	}

  int ret=0;
	for(int i=1;i<=h;i++)for(int j=1;j<=w;j++){
	if(s[i-1][j-1]=='.')ret=max(ret,l[i][j]+u[i][j]+r[i][j]+d[i][j]-3);
	}
	cout<<ret<<endl;

}
