#include <bits/stdc++.h>

using namespace std;

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()

template<typename A, typename B> inline bool chmax(A &a, B b) { if (a<b) { a=b; return 1; } return 0; }
template<typename A, typename B> inline bool chmin(A &a, B b) { if (a>b) { a=b; return 1; } return 0; }

typedef unsigned long long ull;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<int, pii> P;

const ll INF = 1ll<<29;
const ll MOD = 1000000007;
const double EPS  = 1e-10;

int w, h;
string maps[20];
int cost[20][20];

int main() {
	cin >> w >> h;
	REP(i, h) cin >> maps[i];
	
	fill(cost[0], cost[h], INF);
	
	priority_queue<P> pq;
	
	REP(i, h) REP(j, w) {
		if (maps[i][j] == '.') {
			pq.push(P(0, pii(i, j)));
			
			i = h; break;
		}
	}
	
	while (!pq.empty()) {
		P pos = pq.top(); pq.pop();
		
		int c = pos.first;
		int x = pos.second.second;
		int y = pos.second.first;
		
		if (!chmin(cost[y][x], c)) continue;
		
		int dx[4] = {1,0,-1,0}, dy[4] = {0,1,0,-1};
		
		REP(i, 4) {
			int nx = x + dx[i];
			int ny = y + dy[i];
			
			if (!(nx >= 0 && nx < w && ny >= 0 && ny < h)) continue;
			
			int nc = c + (maps[ny][nx] == '#');
			
			if (cost[ny][nx] <= nc) continue;
			pq.push(P(nc, pii(ny, nx)));
		}
	}
	
	int ans = INF;
	REP(i, h) REP(j, w) if (maps[i][j] == '.' && cost[i][j] != 0) chmin(ans, cost[i][j]);
	
	cout << ans << endl;
	return 0;
}