#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  vector<string> s;
  string str, ans = "Yes";
  cin >> H >> W;
  for (int i = 0; i < H; i++) {
    cin >> str;
    s.push_back(str);
  }
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (s[i][j] == '#') {
        if (i - 1 > 0 && s[i - 1][j] == s[i][j]) {
          continue;
        } else if (i + 1 <= H - 1 && s[i + 1][j] == s[i][j]) {
          continue;
        } else if (j - 1 > 0 && s[i][j - 1] == s[i][j]) {
          continue;
        } else if (j + 1 <= W - 1 && s[i][j + 1] == s[i][j]) {
          continue;
        } else {
          ans = "No";
        }
      }
    }
  }
  cout << ans;
  char qq;
  cin >> qq;
  return 0;
}
