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

#define all(c) ((c).begin()), ((c).end())
#define dump(c) cerr << "> " << #c << " = " << (c) << endl;
#define iter(c) __typeof((c).begin())
#define tr(i, c) for (iter(c) i = (c).begin(); i != (c).end(); i++)
#define REP(i, a, b) for (int i = a; i < (int)(b); i++)
#define rep(i, n) REP(i, 0, n)
#define mp make_pair
#define fst first
#define snd second
#define pb push_back
#define debug( fmt, ... ) \
        fprintf( stderr, \
                  fmt "\n", \
                  ##__VA_ARGS__ \
        )

typedef unsigned int uint;
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<vll> vvll;
typedef vector<vi> vvi;
typedef vector<double> vd;
typedef vector<vd> vvd;
typedef vector<string> vs;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int INF = 1 << 29;
const double EPS = 1e-10;

double zero(double d) {
    return d < EPS ? 0.0 : d;
}
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return true; } return false; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return true; } return false; }
#define UNIQUE(v) v.erase( unique(v.begin(), v.end()), v.end() );

template<typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p) {
    return os << '(' << p.first << ',' << p.second << ')';
}

template<typename T>
ostream &operator<<(ostream &os, const vector<T> &a) {
    os << '[';
    rep(i, a.size()) os << (i ? " " : "") << a[i];
    return os << ']';
}

string toString(int i) {
    stringstream ss;
    ss << i;
    return ss.str();
}

const int MOD = 1000000007;
// a^k
ll fpow(ll a, ll k, int M) {
    ll res = 1ll;
    ll x = a;
    while (k != 0) {
        if ((k & 1) == 1)
            res = (res * x) % M;
        x = (x * x) % M;
        k >>= 1;
    }
    return res;
}

struct prepare {
	prepare() {
	    cout.setf(ios::fixed, ios::floatfield);
	    cout.precision(8);
	    ios_base::sync_with_stdio(false);
	}
} _prepare;


int W, H;
vector<string> field1, field2;
vector<pii>* now_hole;
vector<pii> hole1, hole2;

int dx[] = {1, 0, -1, 0};
int dy[] = {0, 1, 0, -1};

bool dfs(int r, int c) {
    if(field1[r][c] == '#')
        return false;

    now_hole->push_back(mp(r, c));
    field1[r][c] = '#';

    rep(i, 4) {
        int ny = r + dy[i];
        int nx = c + dx[i];

        if(0 <= nx && nx < W && 0 <= ny && ny < H &&
                field1[ny][nx] == '.') {
            dfs(ny, nx);
        }
    }

    return true;
}

int main() {
    cin >> W >> H;

    now_hole = &hole1;

    rep(i, H) {
        string str;
        cin >> str;
        field1.push_back(str);
        field2.push_back(str);
    }

    rep(r, H) {
        rep(c, W) {
            if(dfs(r, c)) {
                now_hole = &hole2;
            }
        }
    }

    int ans = INF;
    tr(h1, hole1) {
        tr(h2, hole2) {
            chmin(ans, abs(h1->first - h2->first) + abs(h1->second - h2->second) - 1);
        }
    }

    cout << ans << endl;

    return 0;
}