#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  bool a[h][w], ans = true;
  string s[52];
  for (int i = 0; i < h; i++) cin >> s[i];
  for (int i = 0; i < h; i++)
    for (int j = 0; j <= w; j++) {
      switch (s[i][j]) {
        case '#':
          a[i][j] = true;
          break;
        case '.':
          a[i][j] = false;
          break;
      }
    }
  for (int i = 0; i < h; i++)
    for (int j = 0; j <= w; j++) {
      if (a[i][j] == true)
        if (i != 0) {
          if (a[i - 1][j] == true) continue;
        }
      if (i != h - 1) {
        if (a[i + 1][j] == true) continue;
      }
      if (j != 0) {
        if (a[i][j - 1] == true) continue;
      }
      if (j != w - 1) {
        if (a[i][j + 1] == true) continue;
      }
      cout << "No";
      return 0;
    }
  cout << "Yes";
}
