#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  vector<vector<char>> grid(h, vector<char>(w));
  for (int i = 0; i < (h); i++)
    for (int j = 0; j < (w); j++) cin >> grid[i][j];
  const int dx[4] = {1, 0, -1, 0};
  const int dy[4] = {0, 1, 0, -1};
  bool ans = true;
  for (int i = 0; i < (h); i++)
    for (int j = 0; j < (w); j++) {
      if (grid[i][j] == '#') {
        bool found = false;
        for (int dir = 0; dir < 4; ++dir) {
          int nh = h + dx[dir];
          int nw = w + dy[dir];
          if (nh >= 0 && nh < h && nw >= 0 && nw < w && grid[nh][nw] == '#') {
            found = true;
          }
        }
        if (!found) ans = false;
      }
    }
  if (ans)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
