#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int H, W;
  cin >> H >> W;
  string s[51][51];
  for (int i = 1; i <= W; i++) {
    for (int j = 1; j <= H; j++) {
      cin >> s[i][j];
    }
  }
  for (int i = 0; i <= W; i++) {
    for (int j = 0; j <= H; j++) {
      if ((s[i][j] == "#" && s[i - 1][j] == "#") ||
          (s[i][j] == "$" && s[i - 1][j] == "#"))
        s[i][j] = s[i + 1][j] = "$";
      else if ((s[i][j] == "#" && s[i][j - 1] == "#") ||
               (s[i][j] == "#" && s[i][j - 1] == "$") ||
               (s[i][j] == "$" && s[i][j - 1] == "#"))
        s[i][j] = s[i][j - 1] = "$";
    }
  }
  int ans = 1;
  for (int i = 1; i <= W; i++) {
    for (int j = 1; j <= H; j++) {
      if (s[i][j] == "#") ans = 0;
    }
  }
  if (ans == 1)
    cout << "Yes";
  else
    cout << "No";
  return 0;
}
