#include<stdio.h>
#include<cstring>
using namespace std;
#define nmax 105
long i, j, n, m, ma[nmax][nmax], rez;
char s[nmax];

int main()
{
    /*freopen("a.in","r",stdin);
    freopen("a.out","w",stdout);
    */scanf("%ld %ld",&n,&m);
    gets(s);    ma[1][1]=1; rez=1;
    for (i=1;i<=n;i++)
    {
        gets(s);
        if ((i==1)&&(s[0]=='&'))
            ma[1][1]=rez=0;
        for (j=1;j<=m;j++)
            if ((i!=1)||(j!=1))
            {
                if (s[j-1]=='.')
                {
                    ma[i][j]=ma[i-1][j];
                    if (ma[i][j-1]>ma[i][j])
                        ma[i][j]=ma[i][j-1];
                    ma[i][j]++;
                    if (ma[i][j]==1)
                        ma[i][j]=0;
                    if (rez<ma[i][j])
                        rez=ma[i][j];
                }
            }
    }
    printf("%ld",rez);
    return 0;
}