#include <bits/stdc++.h>
using namespace std;

typedef long long   signed int LL;
typedef long long unsigned int LU;

#define incID(i, l, r) for(int i = (l)    ; i <  (r); i++)
#define incII(i, l, r) for(int i = (l)    ; i <= (r); i++)
#define decID(i, l, r) for(int i = (r) - 1; i >= (l); i--)
#define decII(i, l, r) for(int i = (r)    ; i >= (l); i--)
#define  inc(i, n) incID(i, 0, n)
#define inc1(i, n) incII(i, 1, n)
#define  dec(i, n) decID(i, 0, n)
#define dec1(i, n) decII(i, 1, n)

#define inII(v, l, r) ((l) <= (v) && (v) <= (r))
#define inID(v, l, r) ((l) <= (v) && (v) <  (r))

#define PB push_back
#define EB emplace_back
#define MP make_pair
#define FI first
#define SE second
#define UB upper_bound
#define LB lower_bound
#define PQ priority_queue

#define  ALL(v)  v.begin(),  v.end()
#define RALL(v) v.rbegin(), v.rend()
#define  FOR(it, v) for(auto it =  v.begin(); it !=  v.end(); ++it)
#define RFOR(it, v) for(auto it = v.rbegin(); it != v.rend(); ++it)

template<typename T> bool   setmin(T & a, T b) { if(b <  a) { a = b; return true; } else { return false; } }
template<typename T> bool   setmax(T & a, T b) { if(b >  a) { a = b; return true; } else { return false; } }
template<typename T> bool setmineq(T & a, T b) { if(b <= a) { a = b; return true; } else { return false; } }
template<typename T> bool setmaxeq(T & a, T b) { if(b >= a) { a = b; return true; } else { return false; } }
template<typename T> T gcd(T a, T b) { return (b == 0 ? a : gcd(b, a % b)); }
template<typename T> T lcm(T a, T b) { return a / gcd(a, b) * b; }

// ---- ----

int w, h;
string s[20];
int t[20][20];
int INF = 404;

int di[4] = { 1, 0, -1,  0 };
int dj[4] = { 0, 1,  0, -1 };

int main() {
	cin >> w >> h;
	inc(i, h) { cin >> s[i]; }
	
	bool flag = true;
	inc(i, h) {
	inc(j, w) {
		t[i][j] = INF;
		if(flag && s[i][j] == '.') { t[i][j] = 0; flag = false; }
	}
	}
	
	inc(q, INF) {
		inc(i, h) {
		inc(j, w) {
		inc(k, 4) {
			int ii = i + di[k];
			int jj = j + dj[k];
			if(! (inID(ii, 0, h) && inID(jj, 0, w)) ) { continue; }
			if(s[i][j] == '.' && s[ii][jj] == '.') { setmin(t[ii][jj], t[i][j]); }
		}
		}
		}
	}
	inc(q, INF) {
		inc(i, h) {
		inc(j, w) {
		inc(k, 4) {
			int ii = i + di[k];
			int jj = j + dj[k];
			if(! (inID(ii, 0, h) && inID(jj, 0, w)) ) { continue; }
			if(t[i][j] == q && t[ii][jj] == INF) {
				t[ii][jj] = t[i][j] + 1;
				if(s[ii][jj] == '.') {
					cout << t[ii][jj] - 1 << endl;
					return 0;
				}
			}
		}
		}
		}
	}
	
	assert(false);
}