#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w, a[60][60];
  cin >> h >> w;
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      char ch;
      cin >> ch;
      if (ch == '.')
        a[i][j] = 0;
      else
        a[i][j] = 1;
    }
  }
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if (a[i][j] == 1) {
        if ((i - 1 >= 0 && (a[i - 1][j] == 1 || a[i - 1][j] == 2)) ||
            (i + 1 < h && (a[i + 1][j] == 1 || a[i + 1][j] == 2)) ||
            (j - 1 >= 0 && (a[i][j - 1] == 1 || a[i][j - 1] == 2)) ||
            (j + 1 < w && (a[i][j + 1] == 1 || a[i][j + 1] == 2)))
          a[i][j] = 2;
      }
    }
  }
  int flag = 1;
  for (int i = 0; i < h && flag; i++) {
    for (int j = 0; j < w; j++) {
      if (a[i][j] == 1) flag = 0;
      break;
    }
  }
  if (flag)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
