#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define llong long long

vector<pair<int, int>> pool1;
vector<pair<int, int>> pool2;
int w, h;

void dfs(vector<string> &mapping, int y, int x, bool ispool1) {
    if(!(0 <= y && y < h && 0 <= x && x < w)) return;
    if(mapping[y][x] == '#') return;
    mapping[y][x] = '#';
    if(ispool1) pool1.push_back(make_pair(y, x));
    else pool2.push_back(make_pair(y, x));
    
    dfs(mapping, y-1, x, ispool1);
    dfs(mapping, y+1, x, ispool1);
    dfs(mapping, y, x-1, ispool1);
    dfs(mapping, y, x+1, ispool1);
}

int main() {
    cin >> w >> h;
    vector<string> mapping(h);
    rep(i, h) cin >> mapping[i];

    rep(i, h)
        rep(j, w)
            dfs(mapping, i, j, pool1.empty());

    int dist = 20*20;
    for(pair<int, int> p1: pool1) {
        for(pair<int, int> p2: pool2) {
            dist = min(dist, abs(p1.first - p2.first) + abs(p1.second - p2.second) - 1);
        }
    }
    cout << dist << "\n";
}