#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const long long INF = 1LL << 60;
int main() {
  int H, W;
  cin >> H >> W;
  string S[H];
  const int dx[2] = {1, -1};
  const int dy[2] = {1, -1};
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      cin >> S[i][j];
    }
  }
  bool flg = false;
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (S[i][j] == '#') {
        for (int d = 0; d < 2; d++) {
          const int ni = i + dy[d];
          const int nj = j + dx[d];
          if (ni < 0 or H <= ni) continue;
          if (nj < 0 or W <= nj) continue;
          if (S[ni][j] == '#') {
            flg = true;
          }
          if (S[i][nj] == '#') {
            flg = true;
          }
        }
      }
    }
  }
  if (flg)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
