#include <bits/stdc++.h>
using namespace std;
char a[100][100];
int main() {
  long long h, w;
  cin >> h >> w;
  bool sign = false;
  int sign1 = 0;
  for (int i = 1; i <= h; i++)
    for (int j = 1; j <= w; j++) cin >> a[i][j];
  for (int i = 1; i <= h; i++) {
    for (int j = 1; j <= w; j++) {
      if (a[i][j] == '#') {
        sign1++;
        if ((a[i + 1][j] == '.' || i + 1 > h) &&
            (a[i][j + 1] == '.' || j + 1 > w) &&
            (a[i - 1][j] == '.' || i - 1 <= 0) &&
            (a[i][j - 1] == '.' || j - 1 <= 0)) {
          sign = true;
        }
      }
    }
  }
  if (sign1 == 0) sign = true;
  if (sign1 == 1) sign = false;
  if (sign)
    puts("No");
  else
    puts("Yes");
  return 0;
}
