#include <bits/stdc++.h>
using namespace std;
char a[55][55];
int flag = 0;
int main() {
  int h, s;
  cin >> s >> h;
  for (int i = 0; i < h; i++)
    for (int j = 0; j < s; j++) scanf("%c", &a[i][j]);
  for (int i = 0; i < h; i++)
    for (int j = 0; j < s; j++) {
      if (a[i][j] == '#') {
        if (i != 0) {
          if (a[i - 1][j] == '#') continue;
        }
        if (i != s - 1) {
          if (a[i + 1][j] == '#') continue;
        }
        if (j != 0) {
          if (a[i][j - 1] == '#') continue;
        }
        if (j != h - 1) {
          if (a[i][j + 1] == '#')
            continue;
          else {
            cout << "No";
            return 0;
          }
        }
      }
    }
  cout << "Yes";
  return 0;
}
