#include <bits/stdc++.h>
using namespace std;
const int inf = 1000000007;
const int mod = 1000000007;
const double PI = 3.14159265358979323846;
int dx[] = {1, -1, 0, 0};
int dy[] = {0, 0, 1, -1};
int gcd(int a, int b) {
  if (b == 0)
    return a;
  else
    return gcd(b, a % b);
}
int main() {
  int H, W;
  int s[H][W];
  cin >> H >> 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++) {
      if (s[i][j] == '#') {
        bool f = false;
        for (int k = 0; k < (4); k++) {
          int x = j + dx[j], y = i + dy[i];
          if (x >= 0 && y >= 0 && x < W && y < H) {
            if (s[y][x] == '#') f = true;
          }
        }
        if (!f) {
          cout << "No" << endl;
          return 0;
        }
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
