#include <bits/stdc++.h>
using namespace std;
const int dx[4] = {1, -1, 0, 0};
const int dy[4] = {0, 0, 1, -1};
int main() {
  int H, W;
  cin >> H >> W;
  char grid[H][W];
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      cin >> grid[i][j];
    }
  }
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (grid[i][j] == '.') {
        continue;
      } else if (grid[i][j] == '#') {
        int countBlack = 0;
        for (int k = 0; k < 4; k++) {
          int nx = i + dx[k];
          int ny = j + dx[k];
          if (nx < 0 || nx >= H || ny < 0 || ny >= W) {
            continue;
          }
          if (grid[nx][ny] == '#') {
            countBlack++;
          }
        }
        if (countBlack == 0) {
          cout << "No" << endl;
          return 0;
        }
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
