#include <bits/stdc++.h>
using namespace std;
int main() {
  int H = 0, W = 0, count = 0, cut = 0;
  char sw[60][60];
  cin >> H >> W;
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      cin >> sw[i][j];
      if (sw[i][j] == '#') cut++;
    }
  }
  if (cut == 0) return 0;
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (sw[i][j] == '#' && sw[i - 1][j] == '#' ||
          sw[i][j] == '#' && sw[i][j - 1] == '#')
        count++;
    }
  }
  if (count == 0)
    cout << "No" << endl;
  else
    cout << "Yes" << endl;
  return 0;
}
