#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int H, W;
  cin >> H >> W;
  vector<vector<char>> grid(H + 2, vector<char>(W + 2, 'p'));
  for (int i = 1; i <= H; i++) {
    for (int j = 0; j <= W; j++) cin >> grid[i][j];
  }
  bool ans = true;
  for (int i = 1; i <= H; i++) {
    for (int j = 1; j <= W; j++) {
      if (grid[i][j] == '#') {
        if (grid[i - 1][j] != '#' && grid[i + 1][j] != '#' &&
            grid[i][j - 1] != '#' && grid[i][j + 1] != '#')
          ans = false;
      }
    }
  }
  if (ans)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
