#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  string board[50];
  const int dx[4] = {0, 1, 0, -1};
  const int dy[4] = {1, 0, -1, 0};
  bool can = true;
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      cin >> board[i][j];
      int num = 0;
      if (board[i][j] == '.')
        continue;
      else {
        for (int k = 0; k < 4; k++) {
          int ni = i + dx[k];
          int nj = j + dy[j];
          if (ni < 0 || ni >= H) continue;
          if (nj < 0 || nj >= W) continue;
          if (board[ni][nj] == '#') num += 1;
        }
        if (num == 0) {
          can = false;
          break;
        }
      }
    }
  }
  if (can)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
