#include <bits/stdc++.h>
using namespace std;
int dy[] = {0, 0, 1, -1, 0};
int dx[] = {1, -1, 0, 0, 0};
int main(int argc, char const *argv[]) {
  cin.tie(0);
  ios::sync_with_stdio(false);
  int h, w;
  bool flg = false;
  cin >> h >> w;
  char s[50][50];
  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] == '#') {
        if (i - 1 >= 0 && s[i - 1][j] == '#') flg = true;
        if (i + 1 <= h + 1 && s[i + 1][j] == '#') flg = true;
        if (j + 1 <= w + 1 && s[i][j + 1] == '#') flg = true;
        if (j - 1 >= 0 && s[i][j - 1] == '#') flg = true;
      }
    }
  }
  if (flg)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
