#include <bits/stdc++.h>
using namespace std;
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  int h, w;
  cin >> h >> w;
  char c[55][55] = {};
  for (int i = 0; i < h; ++i) {
    for (int j = 0; j < w; ++j) {
      cin >> c[i][j];
    }
  }
  for (int i = 0; i < h; ++i) {
    for (int j = 1; j < w; ++j) {
      if (c[i][j] == '#' && c[i][j - 1] == '#' ||
          c[i][j - 1] == '#' && c[i + 1][j - 1] == '#') {
        cout << "Yes" << endl;
        return 0;
      }
    }
  }
  cout << "No" << endl;
  return 0;
}
