#include<cstdio>
#include<iostream>
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;
    return 0;
}
