#include <bits/stdc++.h>
using namespace std;
int main() {
  char grid[50][50 + 1];
  int h, w;
  cin >> h >> w;
  for (int i = 0; i < h; i++) {
    cin >> grid[i];
  }
  int judge = 0;
  for (int i = 0; i < h; i++) {
    for (int j = 0; grid[i][j] != '\0'; j++) {
      if (grid[i][j] == '#') {
        int check[4];
        check[0] = (i > 0 && grid[i - 1][j] == '#') ? 1 : 0;
        check[1] = (i < h - 1 && grid[i + 1][j] == '#') ? 1 : 0;
        check[2] = (j > 0 && grid[i][j - 1] == '#') ? 1 : 0;
        check[3] = (j < w - 1 && grid[i][j + 1] == '#') ? 1 : 0;
        judge = check[0] + check[1] + check[2] + check[3];
        if (judge > 0) {
          goto END;
        }
      }
    }
  }
END:
  if (judge > 0) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
  return 0;
}
