#include <iostream>
using namespace std;

int main(void){
  int h, w;
  int flg = 1;
  cin >> h >> w;
  
  string board[50];
  
  for (int i=0; i<h; i++) {
    cin >> board[i];
  }
  
  dx[4] = {1, -1, 0, 0};
  dy[4] = {0, 0, 1, -1};
  
  
  for (int i=0; i<h; i++) {
    for (int j=0; j<w; j++) {
      int flg2 = 0;
      if (board[i][j] == '.') continue;
      
      for (int d=0; d<4; d++) {
        const int ni = i + dx[d];
        const int nj = j + dy[d];
        
        if (ni < 0 or ni >= h) continue;
        if (nj < 0 or nj >= w) continue;
        
        if (board[ni][nj] == '#') flg2 = 1;
      }
      if (flg2 == 0) flg = 0;
    }
  }
  
  if (flg == 0) cout << 'No' << endl;
  else cout << 'Yes' << endl;
  
  return 0;
}