#include <iostream>
#include <stdio.h>
using namespace std;

int n,m,d[110][110];
int main(){
//	freopen("f.in","r",stdin);
	scanf("%d%d",&n,&m);
	int i,j;
	char c;
	for(i = 1; i <= n; i++){
		getchar();
		for(j = 1; j <= m; j++){
			c = getchar();
			if(c == '&')
				d[i][j] = -1;
		}
	}
	if(d[1][1] == 0){
		d[1][1] = 1;
		int last = 1;
		for(i = 1; i <= n; i++){
			for(j = 1; j <= m; j++){
				if(d[i][j] == -1 && d[i - 1][j] < 1 && j > last)
					break;
				else{
					d[i][j] = d[i][j] == -1 ? -1 : max(d[i][j - 1],d[i - 1][j]) + 1;
					last = j;
				}
			}
		}
	}
	int maxim = 0;
	for(i = 1; i <= n; i++)
		for(j = 1; j <= m; j++){
			maxim = max(d[i][j],maxim);
		}
		printf("%d\n",maxim);
			
	return 0;
}