#include <bits/stdc++.h>
using namespace std;
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];
    }
  }
  int dx[] = {0, 0, -1, 1};
  int dy[] = {-1, 1, 0, 0};
  bool ok = true;
  for (int i = 0; i < H; ++i) {
    for (int j = 0; j < W; ++j) {
      if (grid[i][j] == '#') {
        ok = false;
        for (int k = 0; k < 4; ++k) {
          if (i + dx[k] < 0 || i + dx[k] >= W || j + dy[k] < 0 ||
              j + dy[k] >= H)
            continue;
          if (grid[i + dx[k]][j + dy[k]] == '#') {
            ok = true;
            break;
          }
        }
      }
      if (!ok) break;
    }
    if (!ok) break;
  }
  if (ok)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
