#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>;

} int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int h, w;
  cin >> h >> w;
  vector<string> s(h);
  rep(i, h) cin >> s[i];
  constexpr int INF = 1001001001;
  VVI a(h, VI(w, INF));
  rep(_, 4) {
    VVI dp(h, VI(w));
    rep(i, h - 1) rep(j, w - 1) {
      if (s[i][j] == '#') {
        chmax(dp[i][j], 1);
        if (s[i+1][j+1] == '#') dp[i+1][j+1] = dp[i][j] + 1;
        if (dp[i][j] == 1) dp[i][j] = 0;
      }
    }
    rep(i, h) rep(j, w) chmin(a[i][j], dp[i][j]);
    VVI na(w, VI(h));
    vector<string> ns(w, string(h, '.'));
    rep(i, h) rep(j, w) {
      int ni = j, nj = h - 1 - i;
      na[ni][nj] = a[i][j];
      ns[ni][nj] = s[i][j];
    }
    swap(h, w);
    swap(a, na);
    swap(s, ns);
  }
  vector<string> t(h, string(w, '.'));
  rep(_, 4) {
    VVI dp(h, VI(w));
    rep(i, h) rep(j, w) {
      chmax(dp[i][j], a[i][j]);
      if (dp[i][j]) {
        t[i][j] = '#';
        if (i + 1 < h && j + 1 < w) chmax(dp[i+1][j+1], dp[i][j] - 1);
      }
    }
    VVI na(w, VI(h));
    vector<string> ns(w, string(h, '.')), nt(w, string(h, '.'));
    rep(i, h) rep(j, w) {
      int ni = j, nj = h - 1 - i;
      na[ni][nj] = a[i][j];
      ns[ni][nj] = s[i][j];
      nt[ni][nj] = t[i][j];
    }
    swap(h, w);
    swap(a, na);
    swap(s, ns);
    swap(t, nt);
  }
  cout << (s == t ? "Yes\n" : "No\n");
}