
#include<bits/stdc++.h>
using namespace std;
const int N=2005;
int l[N][N],r[N][N],up[N][N],down[N][N];
char s[N][N];
int n,m;
int main()
{
	cin>>n>>m;
	for(int i=1;i<=n;i++) cin>>(s[i]+1);
	for(int j=1;j<=m;j++)
	{
		for(int i=1;i<=n;i++) 
			if(s[i][j]=='.') up[i][j]=up[i-1][j]+1;
			else up[i][j]=0;
		for(int i=n;i>=1;i--) 
			if(s[i][j]=='.') down[i][j]=down[i+1][j]+1;
			else down[i][j]=0;
	}
	for(int i=1;i<=n;i++)
	{
		for(int j=1;j<=m;j++) 
			if(s[i][j]=='.') l[i][j]=l[i][j-1]+1;
			else l[i][j]=0;
		for(int j=m;j>=1;j--) 
			if(s[i][j]=='.')r[i][j]=r[i][j+1]+1;
			else r[i][j]=0;
	}
	int ans=-1;
	for(int i=1;i<=n;i++)
		for(int j=1;j<=m;j++)
		{
			if(s[i][j]=='.')
			{
				ans=max(ans,l[i][j]+r[i][j]+up[i][j]+down[i][j]-3);
			}
		}
	cout<<ans<<endl;
 } 
