#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int H, W;
  scanf("%d %d", &H, &W);
  string s[50];
  for (int i = 0; i < H; i++) {
    cin >> s[i];
  }
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      bool paintable = false;
      if (j != W - 1 && s[i][j + 1] == '#') paintable = true;
      if (j != 0 && s[i][j - 1] == '#') paintable = true;
      if (i != H - 1 && s[i + 1][j] == '#') paintable = true;
      if (i != 0 && s[i - 1][j] == '#') paintable = true;
      if (!paintable) {
        printf("No\n");
        return 0;
      }
    }
  }
  printf("Yes\n");
  return 0;
}
