#include <bits/stdc++.h>
using namespace std;
int dx[] = {-1, 0, 1, 0};
int dy[] = {0, -1, 0, 1};
int ddx[] = {-1, 0, 1, 0, -1, 1, -1, 1};
int ddy[] = {0, -1, 0, 1, 1, 1, -1, -1};
long long gcd(long long x, long long y) {
  if (y == 0)
    return x;
  else
    return gcd(y, x % y);
}
long long lcm(long long x, long long y) { return (x * y) / gcd(x, y); }
int main() {
  int h, w;
  cin >> h >> w;
  char s[h][w];
  for (int i = 0; i < h; ++i) {
    for (int j = 0; j < w; ++j) cin >> s[i][j];
  }
  for (int i = 0; i < h; ++i) {
    for (int j = 0; j < w; ++j) {
      if (s[i][j] == '#') {
        if (i + 1 < h) {
          if (s[i + 1][j] == '#') s[i + 1][j] = s[i][j] = '.';
        } else if (i - 1 >= 0) {
          if (s[i - 1][j] == '#') s[i - 1][j] = s[i][j] = '.';
        } else if (j + 1 < w) {
          if (s[i][j + 1] == '#') s[i][j + 1] = s[i][j] = '.';
        } else if (j - 1 >= 0) {
          if (s[i][j - 1] == '#') s[i][j - 1] = s[i][j] = '.';
        }
      }
    }
  }
  for (int i = 0; i < h; ++i) {
    for (int j = 0; j < w; ++j) {
      if (s[i][j] != '.') {
        cout << "No" << endl;
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
