#include <cstdio>
using namespace std;
short nrmax;
char s[101][101];
void run(short x,short y,short nr)
{
    if(s[x+1][y]=='.') run(x+1,y,nr+1);
    else
    {
        if (nr>nrmax) nrmax=nr;
    }
    if(s[x][y+1]=='.') run(x,y+1,nr+1);
    else
    {
        if (nr>nrmax) nrmax=nr;
    }
}
int main()
{
    short n,m,i;
    scanf("%hd%hd",&n,&m);
    for(i=0;i<n;++i)
    scanf("%s",&s[i]);
    run(0,0,1);
    printf("%hd",nrmax);
    return 0;
}