#include <bits/stdc++.h>
using namespace std;
using vvl = vector<vector<long long int>>;
using vl = vector<long long int>;
using vs = vector<string>;
using vvs = vector<vector<string>>;
bool func(vl s, vl t) { return s[1] < t[1]; }
long long int H, W;
long long int flag = 0;
int main() {
  cin >> H >> W;
  vs v(W);
  for (long long int i = 0; i < H; i++) {
    cin >> v[i];
  }
  vvl grided(H, vl(W));
  for (long long int i = 0; i < H; i++) {
    for (long long int j = 0; j < W; j++) {
      if (v[i][j] == '#') {
        if (i > 0) {
          if (v[i - 1][j] == '#') {
            grided[i][j] = 1;
            continue;
          }
        }
        if (i < H - 1) {
          if (v[i + 1][j] == '#') {
            grided[i][j] = 1;
            continue;
          }
        }
        if (j > 0) {
          if (v[i][j - 1] == '#') {
            grided[i][j] = 1;
            continue;
          }
        }
        if (j < W - 1) {
          if (v[i][j + 1] == '#') {
            grided[i][j] = 1;
            continue;
          }
        }
      }
    }
  }
  for (long long int i = 0; i < H; i++) {
    for (long long int j = 0; j < W; j++) {
      if (v[i][j] == '#') {
        if (flag == 0 && grided[i][j] != 1) {
          cout << "No" << endl;
          flag = 1;
          break;
        }
      }
    }
  }
  if (flag == 0) {
    cout << "Yes" << endl;
  }
  return 0;
}
