#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  char s[h + 2][w + 2];
  int dx[4] = {1, 0, -1, 0};
  int dy[4] = {0, -1, 0, 1};
  for (int x = 0; x < w + 2; x++) s[0][x] = '.', s[h + 1][x] = '.';
  for (int y = 0; y < h + 2; y++) s[0][y] = '.', s[w + 1][y] = '.';
  for (int y = 1; y < h + 1; y++)
    for (int x = 1; x < w + 1; x++) cin >> s[x][y];
  for (int y = 1; y < h + 1; y++)
    for (int x = 1; x < w + 1; x++) {
      if (s[x][y] == '#') {
        bool f = false;
        for (int i = 0; i < 4; i++)
          if (s[x + dx[i]][y + dy[i]] == '#') f = true;
        if (!f) {
          cout << "No";
          return 0;
        }
      }
    }
  cout << "Yes";
}
