#include <bits/stdc++.h>
using namespace std;
char a[50][50];
int main() {
  int m, n;
  scanf("%d%d", m, n);
  for (int i = 0; i < m; i++) {
    for (int j = 0; j < n; j++) {
      scanf("%d", a[i][j]);
    }
  }
  for (int i = 0; i < m; i++)
    for (int j = 0; j < n; j++) {
      if (a[i][j] == '#' && a[i + 1][j] != '#' && a[i - 1][j] != '#' &&
          a[i][j - 1] != '#' && a[i][j + 1] != '#') {
        printf("%d", &"No");
        system("pause");
        return 0;
      }
    }
  printf("%d", &"Yes");
  system("pause");
  return 0;
}
