#include <bits/stdc++.h>
using namespace std;
char grid[60][60];
int H, W;
bool flag;
int main() {
  for (int i = 1; i <= H; i++) {
    for (int j = 1; j <= W; j++) {
      cin >> grid[i][j];
    }
  }
  for (int i = 1; i <= H; i++) {
    for (int j = 1; j <= W; j++) {
      if (grid[i][j] == '#' && grid[i - 1][j] != '#' && grid[i + 1][j] != '#' &&
          grid[i][j - 1] == '#' && grid[i][j + 1] == '#')
        flag = true;
    }
  }
  if (!flag) {
    cout << "Yes" << endl;
  } else {
    cout << "no" << endl;
  }
}
