#include <bits/stdc++.h>
using namespace std;
int main() {
  int X, Y;
  int dx[4] = {0, 0, 1, -1};
  int dy[4] = {1, -1, 0, 0};
  int cnt = 0;
  cin >> X >> Y;
  string board[60];
  for (int(i) = 0; i < (X); ++i) cin >> board[i];
  for (int(i) = 0; i < (X); ++i) {
    for (int(j) = 0; j < (Y); ++j) {
      for (int(k) = 0; k < (4); ++k) {
        int x = i + dx[k];
        int y = j + dy[k];
        if (x < X && x >= 0 && y < Y && y >= 0 && board[i][j] == '.') cnt++;
      }
    }
  }
  if (cnt)
    cout << "No" << endl;
  else
    cout << "Yes" << endl;
  return 0;
}
