#include <bits/stdc++.h>
using namespace std;
vector<vector<char>> a;
int h, w;
int hantei(int i, int j) {
  int re = 0;
  if (i > 0) {
    if (a[i - 1][j] == '#') re = max(1, re);
  }
  if (i < h) {
    if (a[i + 1][j] == '#') re = max(1, re);
  }
  if (j > 0) {
    if (a[i][j - 1] == '#') re = max(1, re);
  }
  if (j < w) {
    if (a[i][j + 1] == '#') re = max(1, re);
  }
  return re;
}
int main() {
  int ans = 1;
  cin >> h >> w;
  a.resize(h);
  ;
  for (int i = 0; i < (int)(h); i++) {
    a[i].resize(w);
    ;
    for (int j = 0; j < (int)(w); j++) {
      cin >> a[i][j];
    }
  };
  for (int i = 0; i < (int)(h); i++) {
    ;
    for (int j = 0; j < (int)(w); j++) {
      if (a[i][j] == '#') {
        ans = min(ans, hantei(i, j));
      }
    }
  }
  if (ans == 1)
    cout << "Yes";
  else
    cout << "No";
  return (0);
}
