#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int H, W;
  cin >> H >> W;
  vector<vector<char>> s(H + 2, vector<char>(W + 2, '.'));
  for (int h = 1; h <= H; h++) {
    for (int w = 1; w <= W; w++) {
      cin >> s[h][w];
    }
  }
  for (int h = 1; h <= H; h++) {
    for (int w = 1; w <= W; w++) {
      if (s[h][w] == '.') {
        continue;
      }
      if (s[h + 1][w] == '#' || s[h - 1][w] == '#' || s[h][w + 1] == '#' ||
          s[h][w - 1] == '#') {
        cout << "Yes" << endl;
        return 0;
      }
    }
  }
  cout << "No" << endl;
  return 0;
}
