#include <iostream>
using namespace std;

int n,m,i,j,sol[105],solmax;
char s[105];

int maxim(int a, int b)
{
    if (a>b) return a;
    return b;
}

int main()
{
    cin>>n>>m;
    for (i=1;i<=m;i++)
        sol[i]=-9999999;
    sol[1]=0;
    cin.getline(s,105);
    for (i=1;i<=n;i++)
    {
        cin.getline(s,105);
        for (j=0;j<m;j++)
        {
            if (s[j]=='&')
                sol[j]=-9999999;
            else
            {
                sol[j]=1+maxim(sol[j],sol[j-1]);
            }
            if (sol[j]>solmax)
                    solmax=sol[j];
        }
    }
    cout<<solmax;
    return 0;
}