#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int INF = 1001001001;
const ll INF_LL = 1001001001001001001LL;
int main(void) {
  int h, w;
  cin >> h >> w;
  vector<string> s(h);
  for (int i = 0; i < (int)(h); i++) cin >> s[i];
  vector<int> dx = {1, 0, -1, 0}, dy = {0, 1, 0, -1};
  if (h == 1 && w == 1) {
    cout << "Yes" << endl;
    return 0;
  }
  bool can_all = true;
  for (int i = 0; i < (int)(h); i++) {
    for (int j = 0; j < (int)(w); j++) {
      if (s[i][j] == '#') {
        vector<bool> can(4, false);
        for (int k = 0; k < (int)(4); k++) {
          int x = i, y = j;
          if (x + dx[k] >= h || x + dx[k] < 0 || y + dy[k] >= h ||
              y + dy[k] < 0)
            continue;
          x += dx[k];
          y += dy[k];
          if (s[x][y] == '#') can[k] = true;
        }
        for (int k = 0; k < (int)(4); k++) {
          if (can[k]) {
            can_all = true;
            break;
          } else
            can_all = false;
        }
        if (!can_all) goto rem;
      }
    }
  }
rem:
  if (!can_all)
    cout << "No" << endl;
  else
    cout << "Yes" << endl;
  return 0;
}
