#include <iostream>
#include <fstream>
#include <algorithm>
#include <stdio.h>
#include <string>
#include <math.h>
#include <vector>
#define pb push_back

using namespace std;

int n,m;
int l[101][101];
string s;

int main()
{

    cin>>n>>m;
    for (int i=0; i<n; i++)
    {
        cin>>s;
        for (int j=0; j<m; j++)
            if(s[j]=='.')
                l[i][j]=1;
            else
                l[i][j]=0;
    }

    for (int i=n-1; i>=0; i--)
    {
        for (int j=m-1; j>=0; j--)
        {
            if(l[i][j])
                l[i][j]=1+max(l[i][j+1],l[i+1][j]);
        }
    }
    cout<<l[0][0];
 return 0;
}