#include <bits/stdc++.h>
using namespace std;
int board_check(char **, int, int);
int main() {
  int H, W, i;
  char **board;
  cin >> H >> W;
  board = new char *[H + 2];
  for (i = 0; i < H + 2; ++i) {
    board[i] = new char[W + 2];
  }
  for (i = 1; i <= H; ++i) {
    char str[W];
    cin >> str;
    strcpy(board[i], str);
  }
  if (board_check(board, H, W)) {
    cout << "Yes" << endl;
  } else
    cout << "No" << endl;
  delete[] board;
  board = 0;
  return 0;
}
int board_check(char **board, int H, int W) {
  for (int i = 1; i <= H; ++i) {
    for (int j = 1; j <= W; ++j) {
      if (board[i][j] == '#') {
        if (board[i][j + 1] != '#' && board[i][j - 1] != '#' &&
            board[i + 1][j] != '#' && board[i - 1][j] != '#') {
          return 0;
        }
      }
    }
  }
  return 1;
}
