#include <bits/stdc++.h>
int main() {
  int r, c;
  std::cin >> r >> c;
  char a[r][c];
  for (int i = 0; i < r; i++) {
    for (int j = 0; j < c; j++) {
      std::cin >> a[i][j];
    }
  }
  int i, j;
  bool f = 0, n = 0;
  for (int i = 0; i < r; i++) {
    f = 0;
    for (int j = 0; j < c; j++) {
      if (a[i][j] == '.') break;
      if (a[i][j + 1] == '#' && j >= 0 && j < c) {
        f = 1;
      }
      if (a[i][j - 1] == '#' && j >= 0 && j < c) {
        f = 1;
      }
      if (a[i + 1][j] == '#' && i >= 0 && i < r) {
        f = 1;
      }
      if (a[i - 1][j] == '#' && i >= 0 && i < r) {
        f = 1;
      }
      if (f == 0) {
        n = 1;
        break;
      }
    }
    if (n == 1) break;
  }
  n == 1 ? std::cout << "No" : std::cout << "Yes";
  return 0;
}
