#include <bits/stdc++.h>
using namespace std;
const double EPS = 1e-14;
const double PI = acos(-1.0);
int main() {
  int h, w;
  scanf("%d %d", &h, &w);
  vector<string> grid(h);
  for (int i = (int)(0); i < (int)(h); i++) {
    cin >> grid[i];
  }
  int d[5] = {1, 0, -1, 0, 1};
  for (int i = (int)(0); i < (int)(h); i++) {
    for (int j = (int)(0); j < (int)(w); j++) {
      if (grid[i][j] == '#') {
        bool flag = false;
        for (int k = (int)(0); k < (int)(4); k++) {
          int dx = i + d[k + 1];
          int dy = j + d[k];
          if (0 <= dx && dx < w && 0 <= dy && dy < h && grid[dx][dy] == '#')
            flag = true;
        }
        if (!flag) {
          printf("No\n");
          return 1;
        }
      }
    }
  }
  printf("Yes\n");
}
