#include<bits/stdc++.h>
namespace {
#pragma GCC diagnostic ignored "-Wunused-function"
#include<atcoder/all>
#pragma GCC diagnostic warning "-Wunused-function"
using namespace std;
using namespace atcoder;
#define rep(i,n) for(int i = 0; i < (int)(n); i++)
#define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; i--)
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
template<class T> bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } else return false; }
template<class T> bool chmin(T& a, const T& b) { if (b < a) { a = b; return true; } else return false; }
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;
const int di[] = {1, 0, -1, 0};
const int dj[] = {0, 1, 0, -1};

} int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  vector<string> s(n);
  rep(i, n) cin >> s[i];
  auto check = [&]() -> bool {
    static vector<string> s2;
    const int n2 = n - 2, m2 = m - 2;
    s2.resize(n2);
    rep(i, n2) s2[i].resize(m2, '.');
    rep(i, n2) rep(j, m2) {
      s2[i][j] = [&] {
        rep(di, 3) rep(dj, 3) if (s[i+di][j+dj] == '#') {
          return '#';
        }
        return '.';
      }();
    }
    assert(s2[0][0] == '.' && s2[n2-1][m2-1] == '.');
    queue<P> q;
    q.emplace(0, 0);
    s2[0][0] = '#';
    auto idxchk = [&](int i, int j) { return 0 <= i && i < n2 && 0 <= j && j < m2; };
    while(q.size()) {
      auto [i, j] = q.front(); q.pop();
      rep(k, 4) {
        int ni = i + di[k], nj = j + dj[k];
        if (!idxchk(ni, nj)) continue;
        if (s2[ni][nj] == '.') {
          q.emplace(ni, nj);
          s2[ni][nj] = '#';
        }
      }
    }
    return s2[n2-1][m2-1] == '#';
  };
  if (!check()) {
    cout << 0 << '\n';
    return 0;
  }
  rep(i, n) rep(j, m) if (s[i][j] == '.') {
    if (i < 3 && j < 3) continue;
    if (i >= n - 3 && j >= m - 3) continue;
    s[i][j] = '#';
    if (!check()) {
      cout << 1 << '\n';
      return 0;
    }
    s[i][j] = '.';
  }
  cout << 2 << '\n';
  return 0;
}