#include <bits/stdc++.h>
using namespace std;
int H, W;
char s[50][50];
bool flag;
bool solve(int a, int b) {
  if (s[a][b] == '#') {
    if (s[a - 1][b] == '#')
      return true;
    else if (s[a + 1][b] == '#')
      return true;
    else if (s[a][b - 1] == '#')
      return true;
    else if (s[a][b + 1] == '#')
      return true;
    else
      return false;
  } else
    return true;
}
int main() {
  cin >> H >> W;
  for (int j = 0; j < H; j++) {
    for (int k = 0; k < W; k++) {
      cin >> s[j][k];
    }
  }
  for (int j = 0; j < H; j++) {
    for (int k = 0; k < W; k++) {
      flag = solve(j, k);
    }
  }
  if (flag)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
