#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  char s[100][100];
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      cin >> s[i][j];
    }
  }
  bool ans = true;
  for (int i = 0; i < H; i++) {
    if (!ans) break;
    int up = i - 1;
    int down = i + 1;
    for (int j = 0; j < W; j++) {
      int right = j + 1;
      int left = j - 1;
      if (s[i][j] == '#') {
        if (up >= 0) {
          if (s[up][j] == '#') break;
        }
        if (left >= 0) {
          if (s[i][left] == '#') break;
        }
        if (down <= H) {
          if (s[down][j] == '#') break;
        }
        if (right <= W) {
          if (s[i][right] == '#') break;
        }
        ans = false;
      }
    }
  }
  if (ans)
    cout << "Yes" << endl;
  else if (!ans)
    cout << "No" << endl;
}
