#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  string s[h][w];
  string sub;
  string ans[h][w];
  for (int i = 0; i < h; i++) {
    cin >> sub;
    for (int j = 0; j < w; j++) {
      s[i][j] = sub[j];
    }
  }
  const int dx[4] = {0, -1, 1, 0};
  const int dy[4] = {-1, 0, 0, 1};
  int count = 0;
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if (s[i][j] == "#") {
        for (int k = 0; k < 4; k++) {
          if (i + dy[k] < 0 || i + dy[k] >= h || j + dx[k] < 0 ||
              j + dx[k] >= w)
            continue;
          if (s[i + dy[k]][j + dx[k]] == "#") {
            count++;
          }
        }
      }
    }
  }
  if (count > 0) {
    cout << "Yes";
  } else {
    cout << "No";
  }
}
