#include <bits/stdc++.h>
using namespace std;
int H, W;
char s[55][55];
int dx[4] = {1, -1, 0, 0};
int dy[4] = {0, 0, 1, -1};
int main() {
  cin >> H >> W;
  for (int i = 0; i < H; i++) {
    scanf("%s", &s[i]);
  }
  bool ans = true;
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (s[i][j] == '#') {
        bool found = false;
        for (int k = 0; k < 4; k++) {
          int i2 = i + dx[k];
          int j2 = j + dy[k];
          if (i2 > 0 && i2 < H && j2 > 0 && j2 < W && s[i2][j2] == '#') {
            found = true;
          }
        }
        if (!found) ans = false;
      }
    }
  }
  cout << (ans ? "Yes" : "No") << endl;
  return 0;
}
