#include <fstream>

using namespace std;

int n,m;
char s[102][102];
int x[102][102];

int main()
{
    int i,j,max=0;
    ifstream fin("stdin");
    fin>>n>>m;
    for(i=0;i<n;i++)
        fin>>s[i];
    fin.close();
    x[0][0]=1;
    for(i=0;i<n;i++)
        for(j=0;j<m;j++)
            if(x[i][j])
            {
                if(j+1<m && s[i][j+1]=='.')
                    if(x[i][j+1]==0 || 1+x[i][j]>x[i][j+1])
                        x[i][j+1]=1+x[i][j];
                if(i+1<n && s[i+1][j]=='.')
                    if(x[i+1][j]==0 || 1+x[i][j]>x[i+1][j])
                        x[i+1][j]=1+x[i][j];
                if(x[i][j]>max)
                    max=x[i][j];
            }
    ofstream fout("stdout");
    fout<<max;
    fout.close();
    return 0;
}