#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  string ans = "Yes";
  char *ptr0 = new char[W];
  char *ptr1 = new char[W];
  for (int j = 0; j < W; j++) {
    cin >> ptr0[j];
  }
  for (int i = 1; i < H; i++) {
    while (i % 2 == 0) {
      for (int j = 0; j < W; j++) {
        cin >> ptr0[j];
        if (ptr1[j] == '#') {
          if ((j + 1 < W && ptr1[j + 1] == '#') ||
              (j - 1 > 0 && ptr1[j - 1] == '#') || ptr0[j] == '#') {
          } else {
            ans = "No";
            i = H + 1;
            break;
          }
        }
      }
      i++;
    }
    while (i % 2 == 1) {
      for (int j = 0; j < W; j++) {
        cin >> ptr1[j];
        if (ptr0[j] == '#') {
          if ((j + 1 < W && ptr0[j + 1] == '#') ||
              (j - 1 > 0 && ptr0[j - 1] == '#') || ptr1[j] == '#') {
          } else {
            ans = "No";
            i = H + 1;
            break;
          }
        }
      }
      i++;
    }
  }
  cout << ans << endl;
  return 0;
}
