#include <bits/stdc++.h>
using namespace std;
char input[50][50];
int dx1[4] = {1, 0, -1, 0};
int dy1[4] = {0, 1, 0, -1};
int n, k;
int dfs(int x, int y) {
  bool flag = false;
  for (int dx = 0; dx < 4; dx++) {
    for (int dy = 0; dy < 4; dy++) {
      int nx = x + dx1[dx];
      int ny = y + dy1[dy];
      if (0 < nx and nx < n and 0 < ny and ny < k and input[nx][ny] == '#') {
        flag = true;
        break;
      }
    }
  }
  return flag;
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  ;
  while (cin >> n >> k) {
    bool flag1 = false;
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < k; j++) {
        cin >> input[i][j];
      }
    }
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < k; j++) {
        if (input[i][j] == '#') {
          if (dfs(i, j) == true) {
            flag1 = true;
          } else {
            flag1 = false;
            break;
          }
        }
      }
    }
    if (flag1 == true) {
      cout << "Yes" << endl;
    } else {
      cout << "No" << endl;
    }
  }
  return 0;
}
