#include<iostream>
#include<cstdio>
#include<algorithm>
#include<string>
#include<vector>
#include<queue>
#include<set>
#include<stack>
#include<functional>
#include<list>
#include<unordered_map>
#include<map>
using namespace std;

int a, b;
string c[102];
vector<int>l, r, x, y;
int dx[4] = { -1,0,0,1 }, dy[4] = { 0,-1,1,0 };
bool S;
void saiki(int n,int  m) {
	c[n][m] = 0;
	for (int i = 0; i < 4; i++) {
		int p = n + dx[i], q = m + dy[i];
		if (p >= 0 && p < a&&q >= 0 && q < b) {
			if (c[p][q] == '&')S = true;
			else if (c[p][q] == '.') {
				saiki(p, q);
			}
			else if (c[p][q] == '#') {
				l.push_back(p);
				r.push_back(q);
			}
		}
	}
}
int main(){
	while (cin >> b >> a, a | b) {
		string t;
		for (int q = 0; q < b + 2; q++)t += ".";
		c[0] = c[a + 1] = t;
		for (int d = 0; d < a; d++) {
			string e; cin >> e;
			c[d+1] = "." + e + ".";
		}
		l.clear(); r.clear(); x.clear(); y.clear();
		saiki(0, 0);
		for (int f = 0;; f++) {
			if (S) { cout << f << endl; break; }
			x = l; y = r;
			l.clear(); r.clear();
			for (int i = 0; i < x.size(); i++) {
				c[x[i]][y[i]] = ',';
			}
			for (int i = 0; i < x.size(); i++) {
				saiki(x[i], y[i]);
			}
		}
	}
}