#include <iostream>

using namespace std;
int m[101][101];
int main()
{
    int lin, col, i, j, max1=0;
    char ch;
    cin>>lin>>col;
    cin.ignore();
    for(i=1; i<=lin; ++i)
        {
            for(j=1; j<=col; ++j)
                {
                    cin>>ch;
                    if(ch=='&') m[i][j]=-1;
                    if(m[i][j]!=-1)
                        {
                            if(i>1) m[i][j]=m[i-1][j]+1;
                            if(j>1&&(m[i][j-1]+1)>m[i][j]) m[i][j]=m[i][j-1]+1;
                            if(m[i][j]>max1) max1=m[i][j];
                        }
                }
            cin.ignore();
        }
    cout<<max1+1;
    return 0;
}