#include <bits/stdc++.h>
using namespace std;
long long mod = 1000000007;
long long mod9 = 1000000009;
signed main() {
  long long h, w;
  cin >> h >> w;
  char s[55][55];
  for (long long i = 0; i < (h + 2); i++) {
    s[0][i] = '.';
    s[w + 1][i] = '.';
  }
  for (long long i = 0; i < (w + 2); i++) {
    s[i][0] = '.';
    s[i][h + 1] = '.';
  }
  for (long long i = 0; i < (h); i++) {
    scanf("%s", s[i + 1] + 1);
    strcat(s[i + 1], ".");
  }
  bool f_field = 1;
  long long ix[4] = {1, 0, -1, 0};
  long long jy[4] = {0, 1, 0, -1};
  for (long long i = 0; i < (h); i++)
    for (long long j = 0; j < (w); j++) {
      if (s[i + 1][j + 1] == '#') {
        bool ff = 0;
        for (long long k = 0; k < (4); k++) {
          if (s[i + 1 + ix[k]][j + 1 + jy[k]] == '#') ff = 1;
        }
        if (ff) f_field = 0;
      }
    }
  if (f_field)
    cout << "No" << endl;
  else
    cout << "Yes" << endl;
}
