#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b;
  scanf("%d%d", &a, &b);
  getchar();
  char c;
  char s[51][51];
  memset(s, 0, sizeof(s));
  for (int i = 0; i < a; i++) {
    gets(s[i]);
  }
  bool flag;
  for (int i = 0; i < a; i++) {
    for (int j = 0; j < b; j++) {
      if (s[i][j] == '#') {
        flag = false;
        if (s[i - 1][j] == '#' || s[i + 1][j] == '#' || s[i][j - 1] == '#' ||
            s[i][j + 1] == '#')
          flag = true;
        else
          break;
      }
    }
  }
  if (flag == false)
    cout << "No" << endl;
  else {
    cout << "Yes" << endl;
  }
  return 0;
}
