#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m, flag = 0;
  char a[1009][1009] = {'&'};
  cin >> n >> m;
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= m; j++) cin >> a[i][j];
  }
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= m; j++) {
      if (a[i][j] == '#' && a[i - 1][j] == '.' && a[i][j - 1] == '.' &&
          a[i][j + 1] == '.' && a[i + 1][j] == '.') {
        flag = 1;
        cout << "Yes" << endl;
        return 0;
      }
      if (a[i][j] == '#' && i == 1 && j == 1 && a[i][j + 1] == '.' &&
          a[i + 1][j] == '.') {
        flag = 1;
        cout << "Yes" << endl;
        return 0;
      }
      if (a[i][j] == '#' && i == n && j == m && a[i][j - 1] == '.' &&
          a[i - 1][j] == '.') {
        flag = 1;
        cout << "Yes" << endl;
        return 0;
      }
      if (a[i][j] == '#' && j == m && i == 1 && a[i - 1][j] == '.' &&
          a[i + 1][j] == '.') {
        flag = 1;
        cout << "Yes" << endl;
        return 0;
      }
      if (a[i][j] == '#' && i == n && j == 1 && a[i][j + 1] == '.' &&
          a[i - 1][j] == '.') {
        flag = 1;
        cout << "Yes" << endl;
        return 0;
      }
      if (a[i][j] == '#' && i == n && a[i][j - 1] == '.' &&
          a[i][j + 1] == '.' && a[i - 1][j] == '.') {
        flag = 1;
        cout << "Yes" << endl;
        return 0;
      }
      if (a[i][j] == '#' && i == 1 && a[i][j + 1] == '.' &&
          a[i][j - 1] == '.' && a[i + 1][j] == '.') {
        flag = 1;
        cout << "Yes" << endl;
        return 0;
      }
      if (a[i][j] == '#' && j == m && a[i][j - 1] == '.' &&
          a[i - 1][j] == '.' && a[i + 1][j] == '.') {
        flag = 1;
        cout << "Yes" << endl;
        return 0;
      }
      if (a[i][j] == '#' && j == 1 && a[i + 1][j] == '.' &&
          a[i][j + 1] == '.' && a[i - 1][j] == '.') {
        flag = 1;
        cout << "Yes" << endl;
        return 0;
      }
    }
  }
  if (flag = 0) cout << "No" << endl;
  return 0;
}
