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