#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  string S[H];
  bool can = true;
  const int dx[4] = {1, 0, -1, 0};
  const int dy[4] = {0, 1, 0, -1};
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      cin >> S[i][j];
    }
  }
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (S[i][j] == '#') {
        bool can_1 = true;
        for (int d = 0; d < 4; d++) {
          int ni = i + dy[d];
          int nj = j + dx[d];
          if (ni < 0 || ni >= H) continue;
          if (nj < 0 || nj >= W) continue;
          if (S[ni][nj] == '#') {
            can_1 = false;
            break;
          }
        }
        if (can_1) {
          can = false;
          goto OUT;
        }
      }
    }
  }
OUT:
  if (can)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
