#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  char A[H][W];
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      cin >> A[i][j];
    }
  }
  int x[4] = {1, 0, -1, 0};
  int y[4] = {0, 1, 0, -1};
  bool flg = true;
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      int cnt = 0;
      for (int s = 0; s < 4; s++) {
        if ((j + x[s]) < 0 || (j + x[s]) >= W) {
          continue;
        } else if ((i + y[s]) < 0 || (i + y[s]) >= H) {
          continue;
        } else {
          if (A[i + x[s]][j + y[s]] == '.') {
            cnt++;
          }
        }
      }
      if (cnt == 4) {
        flg = false;
      }
    }
  }
  if (flg) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
  return 0;
}
