#include <bits/stdc++.h>
using namespace std;
long long int gcd(long long int x, long long int y) {
  while (y != 0) {
    if (x > y) {
      long long int r = x % y;
      x = y;
      y = r;
    } else {
      long long int r = y % x;
      y = r;
    }
  }
  return x;
}
int main(void) {
  long long int H, W;
  int jur = 0, ans = 0;
  cin >> H >> W;
  vector<vector<char>> s(H, vector<char>(W));
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      cin >> s[i][j];
    }
  }
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      jur = 0;
      if (s[i][j] == '#') {
        if (i - 1 >= 0) {
          if (s[i - 1][j] == '#') jur = 1;
        }
        if (i + 1 < H) {
          if (s[i + 1][j] == '#') jur = 1;
        }
        if (j - 1 >= 0) {
          if (s[i][j - 1] == '#') jur = 1;
        }
        if (j + 1 < W) {
          if (s[i][j + 1] == '#') jur = 1;
        }
        if (jur == 0) ans = 1;
        break;
      }
    }
    if (ans == 1) break;
  }
  if (ans == 0)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
