#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  char masu[H + 2][W + 2];
  string line;
  int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
  for (int i = 0; i < H + 2; i++) {
    for (int j = 0; j < W + 2; j++) {
      masu[i][j] = '.';
    }
  }
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      char in;
      cin >> in;
      masu[i][j] = in;
    }
  }
  for (int i = 0; i <= H; i++) {
    for (int j = 0; j <= W; j++) {
      bool flag = true;
      if (masu[i][j] == '#') {
        for (int k = 0; k < 4; k++) {
          int nx = j + dx[k];
          int ny = i + dy[k];
          if (0 <= nx && nx <= W - 1 && 0 <= ny && ny <= H - 1) {
            if (masu[j + dx[k]][i + dy[k]] == '#') {
              flag = false;
              break;
            }
          }
        }
      } else {
        flag = false;
      }
      if (flag) {
        cout << "No" << endl;
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
}
