#include <bits/stdc++.h>
using namespace std;
int main() {
  int X, Y;
  cin >> X >> Y;
  string str[70];
  bool can = false;
  for (int(i) = 0; i < (Y); ++i) cin >> str[i];
  int dx[4] = {1, -1, 0, 0};
  int dy[4] = {0, 0, 1, -1};
  for (int(i) = 0; i < (X); ++i) {
    for (int(j) = 0; j < (Y); ++j) {
      if (j + 1 < Y && (str[i][j] == '.' && str[i][j + 1] == '.')) {
        can = true;
      } else {
        can = false;
        break;
      }
    }
  }
  if (can) {
    cout << "Yes" << endl;
    return 0;
  }
  for (int(i) = 0; i < (X); ++i) {
    for (int(j) = 0; j < (Y); ++j) {
      if (str[i][j] == '#') {
        for (int(k) = 0; k < (4); ++k) {
          int x = i + dx[k];
          int y = j + dy[k];
          if (x < X && y < Y && x >= 0 && y >= 0 && str[x][y] == '#') {
            can = true;
            break;
          }
          if (k == 3 && !can) {
            can = false;
            break;
          }
        }
      }
    }
  }
  if (can)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
