#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int H, W;
  cin >> H >> W;
  char s[H][W];
  for (int i = 0; i < H; ++i) {
    for (int j = 0; j < W; ++j) {
      cin >> s[i][j];
    }
  }
  bool success = true;
  int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
  for (int i = 0; i < H; ++i) {
    for (int j = 0; j < W; ++j) {
      if (s[i][j] == '#') {
        bool can = false;
        for (int k = 0; k < 4; ++k) {
          int nx = i + dx[k], ny = j + dy[k];
          if (0 <= nx && nx < W && 0 <= ny && ny < H && s[nx][ny] == '#') {
            can = true;
          }
        }
        if (!can) {
          success = false;
        }
      }
    }
  }
  if (success) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
  return 0;
}
