#include <bits/stdc++.h>
using namespace std;
const long long int INF = 1e18;
const long long int mod = 1e9 + 7;
struct Edge {
  long long int to, weight;
  Edge(long long int t, long long int w) : to(t), weight(w) {}
};
using graph = vector<vector<long long int>>;
using Graph = vector<vector<Edge>>;
long long int gcd(long long int a, long long int b) {
  if (b == 0) {
    return a;
  } else {
    return gcd(b, a % b);
  }
}
long long int lcm(long long int a, long long int b) {
  return a / gcd(a, b) * b;
}
long long int keta(long long int N) {
  int tmp{};
  while (N > 0) {
    tmp += (N % 10);
    N /= 10;
  }
  N = tmp;
  return N;
}
bool kai(string S) {
  bool flag = true;
  for (long long int i = 0; i < S.size() / 2; ++i) {
    if (S[i] != S[S.size() - i - 1]) {
      flag = false;
      break;
    }
  }
  return flag;
}
long long int h, w;
long long int s[60][60];
string ans = "Yes";
long long int dx[4] = {1, 0, -1, 0};
long long int dy[4] = {0, 1, 0, -1};
void solve(long long int x, long long int y) {
  for (long long int i = 0; i < 4; ++i) {
    long long int nx = x + dx[i];
    long long int ny = y + dy[i];
    if (s[nx][ny] == '#') {
      return;
    }
  }
  ans = "No";
}
int main() {
  cin >> h >> w;
  for (long long int i = 0; i < h; ++i) {
    for (long long int j = 0; j < w; ++j) {
      cin >> s[i][j];
    }
  }
  for (long long int i = 0; i < h; ++i) {
    for (long long int j = 0; j < w; ++j) {
      if (s[i][j] == '#') {
        solve(i, j);
      }
    }
  }
  cout << ans << endl;
  return 0;
}
