#include <bits/stdc++.h>
constexpr long long INFL = 1LL << 60;
constexpr int INF = 1e9;
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  char s[50][50];
  for (int i = 0; i < h; ++i)
    for (int j = 0; j < w; ++j) cin >> s[i][j];
  bool ans[50][50];
  for (int i = 0; i < h; ++i) {
    for (int j = 0; j < w; ++j) {
      if (s[i][j] == '#')
        ans[i][j] = false;
      else
        ans[i][j] = true;
    }
  }
  for (int i = 0; i < h; ++i) {
    for (int j = 0; j < w; ++j) {
      if (j != 0 && s[i][j] == '#' && s[i][j - 1] == '#') {
        ans[i][j] = true;
        ans[i][j - 1] = true;
      }
    }
  }
  for (int i = 0; i < h; ++i) {
    for (int j = 0; j < w; ++j) {
      if (j != 0 && s[j][i] == '#' && s[j - 1][i] == '#') {
        ans[j][i] = true;
        ans[j - 1][i] = true;
      }
    }
  }
  string answer = "Yes";
  for (int i = 0; i < h; ++i)
    for (int j = 0; j < w; ++j)
      if (ans[i][j] == false) {
        answer = "No";
        break;
      }
  cout << answer << endl;
  return 0;
}
